Advanced Functional Materials (AFM)

Global energy consumption is constantly increasing, and the use of fossil fuels is creating drastic changes to global climate. All United Nations Member States have adopted the 2030 Agenda for sustainable development of our world. At the heart of the 2030 Agenda are 17 Sustainable Development Goals (SDGs).

Our research is primarily focused on making progress towards one of these goals – ensuing access to affordable and clean energy (SDG 7). On the one hand, we have been devoting our efforts to exploring environment-friendly solar cells to convert clean solar energy into electricity; on the other hand, we dedicate to developing low-cost and high-performance light-emitting diodes (LEDs) to reduce energy consumption in lighting and displays products.

Solar cells – A clean energy technology

Solar power is an ideal source for renewable and clean energy. Solar cells are semi-conductor devices which use the photovoltaic effect to directly convert solar energy into electricity. Although the current solar cell market is dominated by silicon-based devices, in 2019, just over 2% of global electricity came from solar.
Solution-processed solar cells based on organic semiconductors and metal halide perovskites have the advantages of both high performance and low cost. Especially, they have attractive properties of high absorption coefficients, mechanical flexibility and capability for large-area manufacturing using solution-based printing techniques. Thus, they have shown great potential to significantly promote the widespread use of the solar cell technology, making it possible to generate much more electricity from clean solar energy.

LEDs – Highly energy-efficient light sources

In addition to generating more electricity, it is equally important to improve the energy efficiency of electric devices. Lighting and displays are vital electric devices in our daily life, which also account for the largest amount of electricity consumption. Thus, the adoption of efficient and low-cost lighting and display technologies is in an urgent need to reach the SDG 7. LEDs are semiconductor light sources, which emit light when current flows through them. LEDs are currently considered as the most promising technology in reducing energy consumption in lighting and displays.

Metal halide perovskites, which have led to great advances in photovoltaic devices, have also shown promising optoelectronic properties suitable for LED applications, such as high photoluminescence quantum yields, widely tunable bandgap, and narrow emission width. Perovskite LEDs have progressed rapidly over the past several years and reached high external quantum efficiencies of over 20%. The outstanding development of perovskite LEDs makes them a promising candidate for the next generation of low-cost and highly efficient LEDs for applications in lighting and displays.

Exploiting sustainable energy source is one of the biggest challenges we face now and in the future. “Affordable and clean energy” is the 7th of the17 Goals of the UN’s 2030 Agenda for Sustainable Development. Solar energy as a clean and free energy source should be exploited and will play a main role in the future. Our projects are all align well with exploiting and storing solar energy.

Fig.1 The performance, device structure and a photo of solution-processed semi-transparent organic solar cells. Electricity is a main kind of energy for our daily life. Our main research activity is solution processed Polymer/organic solar cells, which can convert the sunlight into electricity. Organic solar cells can be made on plastic substrates with traditional printing techniques. They can be flexible and transparent as shown in Figure 1.[1] Therefore, they can be installed on curved surfaces and windows. In the past 21 years, we have been working on optimizing processing of fullerene/non-fullerene organic solar cells and studying device physics to deepen understand on the mechanism of devices for enhancing the power conversion efficiency.

The Sunlight varies with time, season, and location on the earth. To extend the application of organic solar cells, storing electricity converted from the sunlight is necessary. Super-capacitors are components, which can store electricity. Collaborated with Prof. Johanna Rosen at IFM, LiU, we developed hybrid super-capacitors based on MXene and polymers. Funded by Swedish research council we worked on integrated organic solar cells with super-capacitors (Photo-supercapacitors (PSCs)). Flexible semitransparent photovoltaic supercapacitors based on water-processed MXene electrodes were realized. Figure 2 displays the photovoltaic and storage performance of the PSC, which has potential applications as portable power units to charge low power consumption electronics/IoT. [2]

The J–V characteristics of the PSCs under two illumination directions.  Photo-charge under different light intensity and galvanostatic discharge at 2 A/cm3 of the PSC.

Currently, collaborating with Karlstad University, Chalmers University of Technology and Lund University funded by Knut and Alice Wallenberg Foundation, our main activity is studying drying process of organic blends to understand the morphology formation from solutions to solid films and the correlation with performance of devices. We also work on understanding the sources of energy losses and transport limitations in organic solar cells collaborated with several Chinese leading groups in the field of organic solar cells.

Contact Principal Investigator:
Fengling Zhang

Additive Manufacturing (AM), also known as 3D printing, is a disruptive digital manufacturing technique for industrial production. It enables the creation of personalized and customized parts that are often lighter, stronger and have a higher degree of complexity and functionality than what can be achieved by traditional manufacturing.

The AM processes transform raw materials such as powder or wire into a dense part that is built layer by layer using an energy source such as laser, electron beam or an electric arc. This allows creation of objects with unique material and structural properties and increased functionality. Furthermore, by utilizing the potential of design optimization, AM makes it possible to print complex parts in a single step. In subtractive manufacturing several individually produced parts must be joined together to achieve the same degree of complexity.

Benefits of AM

This will cut cost, accelerated the time-to-market for new products and minimizes resource consumption. It can also be used for restoring damaged parts of higher demands and promote local and distributed manufacturing and production in an economical and sustainable way. Without a doubt, the AM techniques will further contribute to the development and production of a wide range of products across a growing number of industries including e.g. the aerospace, automotive, energy and medical sectors.

Potential and challenges of AM

However, the AM technologies are still under development and considerable research efforts are still needed before the full potential of AM can be realized. The commercial AM systems available on the market today only use a handful of different materials and the rapid heating and solidification associated with the AM processes remains a challenge. Both defects and the final properties of the materials are highly dependent of the complex thermal history involved in the making of the component.

AM of Metallic Materials

The division of Engineering Materials at LiU is strongly involved in the development and characterization of new metallic materials adapted for AM. The research is done in close cooperation with industrial partners such as material- and AM-hardware producers as well as AM-component end users. The ongoing projects include material development of new nickel and aluminium alloys tailored for AM. Other projects are focusing on optimization of heat treatments and surface post-processing treatments. For the characterization of microstructures, high resolution microscopy and large-scale facilities such as Neutron diffraction is often used.

The support from AFM (Advanced Functional Materials) will be used for research on electron beam powder bed fusion (EB-PBF) of new metallic materials. The simultaneous development of both materials and process conditions will broaden the scope for AM and hopefully contribute to new innovative products and a more sustainable production. Thus, this project will contribute to both goal 9 and 12 of the 2030 Agenda for Sustainable Development.

Contact Principal Investigator:
Johan Movarare

 

We develop advanced materials for a sustainable society. The overarching research goal is a basic scientific understanding of an exciting class of materials that can be used for more efficient energy management in society. The materials we are interested in can be used both to generate environmentally friendly electricity, as power sources for space probes, and for environmentally friendly cooling. Developing these new so-called thermoelectric materials (meaning that they convert heat, such as solar heat and waste heat from motors, computers, or power plants, into usable electricity) is a real scientific challenge. It is not as easy as it sounds. A temperature difference is required between the two ends of the material. In other words, a material is needed that is a bad heat conductor, but at the same time it must be a good electrical conductor in order to be able to get any current out. The opposite is true (diamond is, for example, an electrical insulator but an excellent thermal conductor), but normally good electrical conductivity also means good thermal conductivity.

In order for thermoelectric components to reach widespread use beyond today's niche markets, groundbreaking progress is required. We know what we want to achieve. There is a fairly simple quality measure called ZT that can be calculated if you know a few properties of the material (electrical conductivity, thermal conductivity and its so-called Seebeck coefficient, ie how efficiently the material can convert heat into electricity). The higher the ZT, the higher the efficiency of the component. ZT = 4 is often stated as the target, since the efficiency then becomes in class with, for example, a standard refrigerator. Today's common thermoelectric material has about 1, the very best that has been done so far is just over 2, and there is no clear strategy for reaching 4 with traditional methods. The reason for this is that these properties are interdependent; if you change one of them, the others change to a corresponding degree, so that there is no improvement at all. To move forward, new ideas are required, and what we do is try to control the structure and properties of the materials at the nano level to get around the usual limitations.

We tackle the problem by manufacturing thin films of inorganic and temperature-stable materials. Pioneering advances here will require us to be able to individually tailor the layers of a crystal structure, rather than utilizing an inherently stable crystal structure as in commonly occurring ceramics. This enables methods to manufacture new materials, where we investigate thin-film and 2D synthesis far from thermodynamic equilibrium. The scientific impact thus lies in the pioneering understanding of new materials with tailor-made thermal and electronic properties, realized with innovative thin-film synthesis methods.

TEM image of nanolaminate thin film for energy harvesting purposes Contact Principal Investigator:
Per Eklund

The project concerns application-inspired basic research on functional ceramics. Materials range from nitrides, carbides, borides, and oxides. Structures are designed from single-crystals (epitaxial layers), multilayers, superlattices, and nanocomposites. Applications cover wear resistance, oxidation protection, electric contacts, and diffusion barriers for electronics. Research challenges concern the dynamics of growth from the vapor phase, surface science, diffusion/segregation, interfaces, and relationships to properties, with the goal being the ability to design, at the atomic scale, new artificial materials and structures. For film growth, kinetic and thermodynamic parameters are incorporated in multiscale models of nanostructure formation. Film synthesis include UHV magnetron sputtering epitaxy. Simulations of diffusion coefficients are carried out from first principles and molecular dynamics simulations. The monochromated double-aberration corrected ultra-electron microscope Titan³-Arwen in the Ångström Building at LiU Campus Valla procured by Hultman is employed for unsurpassed analytical lattice resolution analyses. The project promotes collaboration with several AFM teams, industry as well as internationally.

For societal impact, the materials and processing developed in the project reduces consumption of energy and resources in each step of the material’s fabrication and its operation. By using physical vapor deposition (instead of high-temperature chemical vapor deposition) and employing our original ion-assisted deposition techniques, less energy is needed for making high-performance materials. By targeting material development for low-friction surfaces in mechanical contacts and/or higher-wear-resistance for cutting tools and drills, less power and energy as well as less (scarce) resources are needed in machine operation and shaping/forming industry, respectively. By producing targeted novel electronic materials, more energy-efficient microelectronics can be designed. For electric contacts, limited-resource gold [Au] may be replaced by our developed electrically conducting nano-laminated ceramics. Our processing requires no hazardous chemicals and offer possibility to replace such presently used by traditional technology. Thus, the project contributes directly and significantly to several UN Agenda 2030 Sustainable Development Goals sustainable-development goals, most noted: #7 (renewable and fossil-free energy), #8 (good jobs and economic growth), #9 (resilient infrastructure and industrialization), and #13 (climate action) – and beyond.

Contact Principal Investigator:
Lars Hultman

The AFM grant is paying part of the salary of Xavier Crispin to lead the group of Organic Energy Materials as a research unit at the Laboratory of Organic Electronics, ITN. We exploit and investigate the physics and chemistry of new organic and composite materials to improve electronic and electrochemical ENERGY devices. One key advantage of organics is that they are composed of atomic elements of high natural abundancy, which is highly relevant for mass implementation of energy devices. Organic materials are also easily tailor-made via organic chemical synthesis. Energy devices can be separated into conversion and storage devices. Here are research topics that are explored:
(i) We functionalize forest-based materials in organic batteries. Firstly, we functionalize lignin and make nanocomposite for electrodes in solid state batteries. Secondly, we use nanocellulose to create ionic selective membrane for organic redox flow batteries.

The image above illustrates the formation of green sustainable materials for large scale stationary batteries. Lignin nanopowder is intimately mixed with carbon black nanopowder to form a forest-based nano-composite that serves as electrode materials in novel organic batteries.

(ii) We study the conversion of heat into electricity through several effects: Seebeck effect of electronic charge carriers, Soret effect of ions and thermogalvanic effect of redox molecules. We also investigate the reverse effect for cooling applications.

(iii) We explore the conversion of electricity into chemical energy via electrolysers for H2 and H2O2 production by using conducting polymer electrocatalysts.

(iv) We design new material structure by additive manufacturing for thermoelectric and piezoelectric heat-to-electricity and vibration-to-electricity conversion.
The Organic Energy Material group is involved in the EDUCATION of Phd students and contributes to several high-level courses (scientific instrumentation, organic electronics, electrochemistry). Our researchers interact with other scientists within several competence centers and research training network.

We also promote INNOVATION by supporting start-up companies as scientific advisers and promoting parallel research and development project (Ligna Energy AB on organic batteries, PARSNORD on thermoelectrics and CELLFION on ionic selective membranes). We also establish long term collaborations with key industrial partners (Redoxme, IMRA-Europe, BillerudKorsnäs).

The UN goals targeted are the followings: 4= Quality Education, 7= Affordable and Clean Energy, 9= Industry, innovation and infrastructure

Three of the UN goals

Contact Principal Investigator at link below:
Xavier Crispin

Materials discoveries at extreme conditions: a path towards new advanced materials

I. A. Abrikosov

Knowledge-based design of new materials is a prerequisite for sustainable development of the society. New and improved materials are strategically important for modern technologies, not least for better resource management, reduced energy consumption and a better quality of life and a cleaner environment. However, discovering new materials is a time-consuming process. In this project, we will explore a novel and highly promising path for accelerated materials discovery. We will use extreme conditions, ultra-high pressure and temperature, to influence the potential energy landscape and to greatly enhance the likelihood to synthesize not only thermodynamically stable, but also so-called metastable materials (perhaps the most well-known example of such a metastable material is diamond, the very hard crystalline phase of pure carbon which is stable under high pressures. It should transform to the soft graphite at ambient pressures but we all know that diamonds do not disappear).

The overall goal of the research proposed in this project is to develop theoretical methods that allow us to understand and quantitatively predict the properties of materials at extreme conditions, and to use them to generate knowledge and to guide discoveries of new materials in real physical experiments carried out in collaborations with other AFM researchers as well as with leading international groups in the field. We will conduct theoretical investigations of the fundamental properties of materials at extreme conditions based on quantum mechanical calculations, as well as employing novel approaches, including machine learning and artificial intelligence. We will develop methods that more reliably take into account the effect of high temperature and complex interaction between electrons when calculating the material properties.

New simulation tools will be used to discover advanced materials with strategic potential. We will use supercomputers to predict their physical properties. Instead of using the theory to explain known experimental facts, we will use it to make qualitative predictions. By making simulations for a large number of materials, we will build data bases of materials properties which would be available for experimentalists and engineers. Supplementing the experience-based material design with our predictive theory, we will accelerate the entire development process. The advantage of carrying out research in this way is first and foremost that we can test much more materials and investigate their properties on a broader scale. Moreover, it is possible to test unexpected combinations of substances that no one else would have tested.

The knowledge gained through our theoretical studies will be used in direct collaboration with experimental researchers and industry. The theoretical studies will be followed up with unique experiments, e.g. in the so-called double-stage diamond anvil cells that allow for a compressions of 10 mln. bars (1 bar correspond to the atmospheric pressure). The combination of theory and experimental method is extremely powerful for achieving breakthroughs in materials physics. In concrete terms, we hope that novel materials with properties attractive for applications will be discovered as a direct result of the project, for example hard materials for high-quality cutting tools. In fact, in this project we collaborate with leading Swedish companies, Sandvik Coromant and Seco Tools, making our research directly relevant for achieving United Nations Sustainable Development Goals 9 (Industry, Innovation and Infrastructure) and 12 (Responsible Consumption and Production).

Figure 1. Ultraincompressible hard rhenium nitride pernitride Re2(N2)(N)2 was discovered at high pressure and stabilized at ambient conditions. Shown is the charge density map of Re2(N2)(N)2 that explains the combination of incompressibility (due to the presence of N1-N1 dumbbells) and high hardness (due to strong covalent bonds between N2 and Re atoms). From Nature Commun. 10, 2994 (2019).

With increasing environment concern and rapidly decreasing amount of other conventional energy resources, harvesting energy from sunlight using
photovoltaic technology and saving energy by maximizing device efficiency are currently being recognized as essential components of future global energy management. In the case of photovoltaics, nanowire (NW) architecture of solar cells provides potential advantages over the planar design as it allows one (i) to reduce material consumption; (ii) to improve absorption of solar energy due to light trapping within NWs arrays; (iii) to tune material properties using band structure engineering; and (iv) to increase defect tolerance due to efficient strain relaxation in NWs.
The solar cell efficiency can be further improved using the so-called intermediate band approach, where the intermediate band serves as a stepping stone for light absorption. The promising materials that can contain the intermediate band are novel alloys made of highly mismatched (HM) III-V semiconductors. These materials are derived from conventional III-V semiconductors such as (Ga,In)(P,As) by the insertion of N or Bi atoms into the group V sublattice. These materials exhibit unusual energy band structure with a narrow band of states located in the band gap of the host material suitable as the intermediate band.
Utilization of HM alloys also allows realizing energy efficient light emitting devices within the green-amber (based on GaN(As)P) and near-infrared (based on GaNBiAs) spectral ranges. In the case of GaNP, addition of nitrogen leads to transformation of the band gap character from an indirect bandgap in GaP to a quasi- direct band one in GaNP. This dramatically increases light emission efficiency of the alloy within the green-yellow-amber spectral range. The latter is currently difficult to realize using other material systems and is required for white lighting applications. GaNBiAs alloys, on the other hand, is a promising material for longer-wavelength applications as their bandgap energy can be tuned within the infra-red spectral range. This range is of great significance in photovoltaics, medical diagnosis and for fibre- optic data/telecommunication.
In this project we suggest to combine advantages of novel nanostructure architecture with those offered by HM alloys, for the next generation of solar cells with record efficiencies and efficient nanoscale light emitters.
The specific aims of the program are:

1.  to understand key material-related parameters of novel nanowires (NWs) from highly mismatched semiconductors (such as dilute nitrides and dilute bismides), and their dependence on structural design;
2. to gain general knowledge on unknown fundamental properties of different crystal polytypes of such NWs, to exploit band structure engineering, and to explore spin-enabling new functionality for potential applications in optoelectronics and photovoltaics;
3. to single out optimum structural design of prototype NW solar cells for efficient energy harvesting utilizing an intermediate-band approach and of prototype NW LEDs with a high efficiency.

We expect that our results will contribute to energy savings and the development of affordable and clean energy, which is defined as sustainability Goal 7 in UN Agenda 2030.

Formidable efforts are invested world-wide on two-dimensional (2D) materials research. With only a few exceptions, all 2D materials originate from van der Waals crystals, that can be mechanically exfoliated (cf. graphene). The primary exception, MXene, is produced by chemical exfoliation, i.e. selective etching of recurring layers in 3D layered precursor solids. Figure: Schematic of sheets of 2D metal carbide, MXene, with ordered vacancies Based on selective etching of compounds from the vast library of layered solids, we are working on a theoretical project to predict new multifunctional 2D materials, beyond MXenes, for fundamental research and advanced engineering. We intend to synthesize materials and apply them to exciting research areas, including energy storage and catalysis. The major scientific challenges include: i) 3D precursor identification and processing, ii) understanding the complex physics/chemistry of 3D→2D conversion, and iii) atomic-scale control during and post-synthesis, for property tailoring.

Our research concerns fundamental studies of crystals, quasi-2D structures, nanostructures, thin films, interfaces and devices based on organic semiconductors and metal halide perovskites. We carry out material/film growth, characterization of (opto)electronic, chemical and structural properties and design of desired material functionality in devices. We strive to do fundamental science on topics that have “real world” application and contribute to a sustainable society.

In this AFM-funded project we explore the surface physics and chemistry of materials and interfaces that have applications in energy conversion or regulation. We use photoelectron spectroscopy (home-lab, e.g. MAX IV), scanning force microscopy, x-ray absorption spectroscopy (e.g. MAX IV), electron microscopy, optical spectroscopy and several (opto)electronic characterization techniques. Our focus mainly is on photovoltaic devices based on organic semiconductor or metal halide perovskites where we explore the interdependence of (opto)electronic-chemical-structural properties at hetero-interfaces and how such interfaces affect device performance in terms of film growth, device/material stability, photon-to-free-charge conversion, charge transport and charge extraction. By obtaining a fundamental understanding of the physics of these processes, we hope to assist in the development of improved materials and devices for solar energy conversion. We collaborate on these topics with a number of researchers that provide complementary expertise in e.g. materials synthesis, (fast) optical spectroscopy, x-ray diffraction spectroscopy and device physics, both within and outside of the AFM SFO.

Figure 1. Simplified sketch of an organic solar cell featuring a donor-acceptor semiconductor blend that self-organizes into nanostructures that provide interfaces for photon-to-free-charge conversion and pathways for electron and hole transport. The donor-acceptor interfaces can be modelled by fabrication of planar interfaces with specific intermolecular orientation: edge-on:edge-on, edge-on:face-on and face-on:face-on that then are characterized and correlated to corresponding device structures.

This project concerns the discovery of a new material. The best description of the material is that it is similar to a mycelium, that is, the root system of fungi. However, in this case the scale is a thousand times smaller. The individual filaments extend in a chain, which can be several micrometers long.

Unlike other inorganic materials that extend in one dimension, such as threads or ribbons, these are significantly thinner. They are so thin in diameter that they correspond to the thickness of two-dimensional materials. Thus, the material should also exhibit an unsurpassed surface area in relation to its weight.

The latter is important in applications where large surface areas are essential for the functionality, for example in water filtering. The same applies to energy storage, catalytic production of hydrogen from water and for the capture of, for example, carbon dioxide from exhaust.

In my research, I plan to investigate the structure and chemistry of this material, and to develop it within the latter two applications. To this end, I will employ advanced electron microscopy combined with in situ methods for exposing the structures to gaseous conditions at high temperatures.

In addition to exhibiting properties that can be crucial in these applications, the material is also manufactured in an industrially scalable manner. Traditional two-dimensional materials in these applications are often produced by a costly top-bottom process. In contrast, these materials are customs-processed through a bottom-up process of cheap and industrially available ingredients, which can have an impact outside the research lab.

Hydrogen is a storable energy carrier that can be readily transformed to electric energy in hydrogen fuel cells. If produced electrochemically by electrolysis using renewable energy sources it would represent a solution to a sustainable fuel production, as long as the electrochemical reactions can proceed with low energy losses. The used electrocatalysts are the keys to mitigate low energy losses. For the hydrogen generation under acidic conditions, noble metals, such as platinum and iridium have for long been regarded as the champion material. Although non-noble metal alternatives are reported to exhibit good catalytic activity, they have not been able to outcompete noble metal-based catalysts regarding both efficiency and stability. For large scale application of electrochemically generated hydrogen the need of noble metals must be drastically reduced. The approach taken is to use nanoparticles, and thereby increase surface/volume ratio and as a second step alloying the noble metal with less expensive transition metals such as nickel or titanium. An even higher utilization of the noble metal can be obtained if the nanoparticles are in the form of a noble metal shell and an inexpensive metal core. For the nanoparticles to be effectively utilized as electrodes in the electrochemical process, they all need to be electrically connected to the electrical terminals of the electrochemical cell.

In the present project we are designing alloyed and core/shell nanoparticles by combining noble metals with a magnetic metal. These magnetic nanoparticles can be self-assembled in magnetic fields and form a highly electron conducting porous material that have the potential to be used as highly effective electrodes in polymer electrolyte membrane (PEM) electrolysis devices. Figure 1 below illustrates a platinum/nickel-alloy (Pt_0.05Ni_0.95) nanoparticles that show excellent performance in our initial tests and figure 2 iron nanoparticles assembled in a 3-d network on a carbon fiber.

Spintronics, which explores the spin degree of freedom instead of or in addition to electron charge, seeks to fill the need for new technologies when the miniaturization of the present-day microelectronics is rapidly approaching its limit. Interest in spintronics is also motivated by the intriguing fundamental science underlying spin-dependent phenomena that are of entirely quantum mechanical nature. Taking advantage of the spin is expected to pave the way for improving performance and adding new functionality to existing devices, but more importantly it could potentially provide a novel platform for future electronics, photonics and information technology leading to new devices like magnetic RAM, spin transistors, spin light-emitting diodes (LED), spin lasers, and spin-based quantum computers, which can outperform existing devices and extend scaling in speed, size and other capabilities at a much lower energy consumption. It could also allow integration of data processing and storage capabilities thus far carried out separately, and to merging of electronics, photonics and magnetics into single technologies with multifunctional devices and integrated systems.

Similar to rectifiers, transistors, LEDs, lasers, etc. in conventional charge-based electronics/photonics, future semiconductor spintronics/spin-photonics are expected to be based on fundamental building blocks, such as spin filters, spin amplifiers, spin detectors, spin light-emitting devices. Unfortunately, such basic spin components are so far still lacking or ineffective at room temperature. Furthermore, a semiconductor material system where these spin functionalities can be incorporated and integrated, preferably based on a mature technology used in present-day electronics/photonics, has yet to be identified. 

The purpose of this project is to conduct in-depth experimental studies of an unconventional approach of defect-enabled spin functionalities in a semiconductor, and to explore such spin engineering for efficient spin filtering, spin amplification and spin detection at room temperature. These room-temperature spin functionalities will be implemented in an interesting and newly emerging material system based on III-V compound semiconductor nano- and quantum-structures such as zero-dimensional (0D) quantum dots and one-dimensional (1D) nanowires, employing Ga(In)NAs as a spin-filtering medium, which is fully compatible with the mature GaAs technology widely used today. Our specific scientific aims are 

1. to understand and tailor key physical and material properties that are important for the defect-enabled spin functionalities; 
2. to develop fundamental building blocks for spintronics and spin-photonics, such as spin injectors, spin amplifiers and spin detectors; 
3. to explore prototype spintronic and spin-photonic devices, such as spin-LEDs, spin lasers and spin transistors.

Early detection and diagnosis of, for example, cancer enables effective treatment and increases the chances of a good prognosis. This needs to drive development forward both regarding image processing methods and contrast agents. New tools are needed to improve the possibilities for early detection and diagnosis, as well as earlier therapeutic treatment.

Photoemission electron microscopy (PEEM) and imaging X-ray photoelectron spectroscopy (XPS) have over the years been powerful tools in classical surface physics and material sciences. However, due to recent technological advances, their uses within other fields/disciplines are rapidly growing. Lately, the XPS/PEEM based elemental analysis and characterization in imaging mode, with exquisite spatial resolution and high sensitivity, has shown the potential to deliver new mechanistic insights in functional nanomaterials and their role in biomedical imaging and therapy.

Our aim is to develop nanoprobes for imaging and targeting purposes. In this project, we visualize biological processes on the cellular level, with the additional dimension of topographical morphology and element specific information, mapping chemical composition and chemical states. This is hereby demonstrated by combined PEEM and imaging XPS investigation of neutrophils and their activation processes, where fluorescence microscopy commonly used in biology is used for benchmarking.

These methods pave the way for element specific imaging of biobased structures on surfaces as well as nanoparticle tracking in the submicro- and nanoregions. The long-term goal of nanoprobe-enhanced inhibition of malignant tumor growth.

Our advanced Photoemission Electron Microscopy (PEEM) and imaging X-ray Photoelectron Spectroscopy (imaging XPS) UHV system for analysis of bio-systems and nanomaterials. Recent PEEM and imaging XPS results of human neutrophil granulocytes are presented. (a) PEEM image of two cells on a silicon oxide surface. (b, c, and d) imaging XPS with element specific analysis. The atomic percent distribution presented in color, where carbon (red), nitrogen (green) and phosphorus (purple). Contact Principal Investigator:
Kajsa Uvdal

Climate change induced by fossil fuel use threatens the well-being and very existence of our societies. The vision of this program is to contribute to the transition to electric transportation (solid-state powered cars, planes, trains, ships), and to loss-reduced conversion and distribution of electricity (solid-state powered grid). High current-voltage ratings, reliability, and cost are key factors in future semiconductor devices needed to achieve this goal. Very high costs, limited voltage range, and surge in demand have set limits for contemporary technologies.

Figure 1: Develop extreme bandgap (Al,Ga)2O3 materials and power devices for enabling CO2-emission-free electric transportation and energy-efficient power grid. The extreme bandgap material aluminium gallium oxide (Al,Ga)2O3 (AlGO) exceeds the electric breakdown voltage of any semiconductor currently employed in power electronics and could enable a future carbon emission free transportation infrastructure as well as a loss-less power grid. For example, field effect transistors with ultrathin layers of extreme bandgap AlGO have the potential to control megawatts at tens of thousands of volts. However, the lack of synthesis control, and lack of knowledge about fundamental properties, hinder the implementation of AlGO within electronic power device concepts. Excitingly, the monoclinic symmetry of the AlGO crystal lattice gives rise to anisotropic physical properties and unconventional phenomena that may be exploited in novel functionalities. This program is designed to tackle the unknown fundamental science by employing multiple pronged approaches: Materials growth and defect engineering; Transport properties optimization; Advanced defect characterization, and Device engineering. Our main objectives are:

• To synthesize high-purity AlGO epitaxial materials with superior control over incorporation of different chemical species and defects by employing our novel and unique chemical vapor deposition method.
•  To develop highly sensitive photo-modulated and temporal resolved Terahertz spectroscopic techniques for studying and minimizing defects and for optimizing transport in AlGO structures.
• To design and fabricate AlGO transistor structures using ion-implanted components and anisotropic charge confinement for control of megawatts at tens of thousands of volts

The PI team members uniquely combine excellence in syntheses and material properties, growth of superior purity materials, advanced defect and free carrier characterization, and cutting-edge semiconductor power device design. Synergy and approach will excel our team to first demonstration the potential of (Al,Ga)2O3 for power devices capable of controlling Megawatts at tens of thousands of Volts, and to lead word-wide efforts in the emerging field of extreme bandgap power materials. The program has the huge potential to radically change transportation and the distribution and conversion of energy in the very near future irrevocably reversing our societies’ reliance on carbon emission and hence contributing to UN sustainable development goal No. 7 Affordable and Clean Energy; No.9 Industry, Innovation and Infrastructure, No. 11 Sustainable Cities and Communities and No.13 Climate Action.

Contact Principal Investigator:
Vanya Darakchieva

Due to the rapidly increasing cooling need in modern society and insufficiency of vapour-compression refrigeration technique, solid-state cooling systems that require no compressors and conventional liquid-vapour refrigerants have been explored as an alternative cooling solution. As an alternative promising cooling method, thermoelectric cooling is based on the Peltier effect that is proportional to the applied current through a junction between two materials with dissimilar thermal power. The challenge is to reduce the high-energy consumption from having a constant current, which also leads to inevitable Joule heating.

In this project, we will demonstrate the electric-induced ionic cooling effect in electrolytes, which will lead to a new class of cooling systems. Similar to the electronic thermoelectric effect, the ionic thermoelectric effect in electrolytes is related to thermodiffusion of charge carriers (anions and cations) under a temperature gradient , . Theoretical studies imply that the reverse effect should be able to perform a refrigerator function . As shown in Figure 1a, the hypothesized working principle is based on an electrolyte containing cations and anions with different “heat of transport”, which under an electric potential will lead to heat flow from one electrode to another via ion migration and condensation. This novel cooling concept will enable low cost, scalable temperature regulation systems with optimized high cooling power and efficiency (COP), which has the potential to fill the vacancy of existing solid-state cooling methods, as illustrated in Figure 1b. The materials involved in the ionic cooling devices are mostly organic and composed of earth abundant elements that are suitable for low cost, large-scale manufacturing. By developing a novel platform for studying the entropy change in electrolytes, we will provide new insights of the ionic behaviour in complex electrolytes and their thermoelectric performance.

Figure 1. Concept of ionic cooling. a. Illustration of the working principle of electric-induced ionic cooling effect b. Expected performance of ionic cooling devices.

Contact Principal Investigator:
Dan Zhao

Artificial Intelligence, the Internet of Things, and Brain-Machine Interfaces have the potential to revolutionize our life by connecting everything and everyone to the cloud. Organic electronics, where the semiconductor is typically an organic polymer, could enable this vision by offering unique features like versatile chemical design and synthesis, solution processability, mechanical flexibility, and biocompatibility that can support endless new functions. However, a key obstacle common to nearly all applications is the absence of stable organic conductors.

Figure 1, Conventional vs proposed mutual doping based on GSCT We recently discovered a method to achieve stable and conductive organic materials that has the potential to overcome the limitations above and to enable truly distributed organic electronic devices and systems for the future Internet of Everything. Our approach is based on the newly discovered effect of mutual doping in polymer donor-polymer acceptor (all-polymer) blends [Nat. Mater. 19, 738-744 (2020)], enabling the development of highly conductive dopant-free organic conductors (Fig. 1). These materials have the potential to outperform traditionally molecular-doped organic conductors by solving problems related to poor material/device stability and the diffusion of dopants into adjacent layers. However, to turn our groundbreaking discovery into a truly disruptive technology in organic (opto)electronics and bioelectronics, we must first obtain a detailed fundamental understanding of the GSCT mechanisms in all-polymer blends.

We aim to achieve this by:
(i) developing all-polymer blends with high electrical conductivity by exploring new materials and combinations thereof that have optimal electronic and electrical properties for maximizing the effect of mutual doping.
(ii) understanding the mechanisms of mutual doping and charge transport in these all-polymer blends by deriving relevant structure-properties relationships.
(iii) developing dopant-free organic electronic devices outperforming traditionally molecular doped devices by integrating all-polymer blends in prototype energy harvesting and electrochemical devices.

The development of dopant-free organic conductors, as proposed here, is expected to solve issues related to instability and low electrical conductivity. I anticipate that implementing this new class of materials in organic optoelectronics and bioelectronics will pave the way toward developing a new generation of highly efficient and biocompatible electronic devices. The impact of this project will be at three levels: i. New materials design/combinations, ii. New physics of charge transfer/transport, iii. New thin-film semiconductor architectures, devices, and applications, with boundless potential in Internet of Things and Brain-Machine Interfaces, so to enable the vision of a truly connected life. This project will also contribute to developing electronic materials with high stability, sustainability, and recyclability, in line with the UN Sustainable Development Goals 12.

Contact Principal Investigator:
Simone Fabiano

Materials science and in particular development of new alloys has a pivotal role to play for the human society to succeed in reaching the global goals for 2030 agreed on by the UN General assembly.[1] In particular, the goals of taking climate action, providing clean and affordable energy, developing industry, innovations and infrastructure, and reaching a responsible consumption and production of resources, all heavily depend on the development of new alloys and metallurgical processes. In a Swedish context the steel and other alloy industries together account for more than 12% of all greenhouse gas emissions.[2] Novel alloys that display improved properties has thus a strong potential to reduce materials and energy usage and lower environmental impacts.

The global goals only give us eight more years, and the urgency is motivated, by the need to reduce our carbon footprint, while at the same time lifting the whole world out of energy poverty. There is no longer available the millennia it took to develop metallurgy from small copper jewellery into todays steel industry, or the century it took for quantum physics to take us from the photo-electric effect to supercomputers. The path to accelerate materials science to meet this urgency goes through use of theoretical modeling, massive parallel computations, and materials big-data analysis.[3]

In this project a theoretically led search for novel alloys with ultra-large lattice distortions is conducted. Large lattice distortions, where atoms displace from ideal crystal sites, and bond-lengths show a large spread in values, have been shown to influence dislocations in several ways and allowing for unusual and beneficial combinations of mechanical properties which are critical for improved structural materials. Furthermore, they reduce thermal conductivity, contribute to anomalous thermal expansion, and slow down corrosion. However, it is also known from the Hume-Rotery rules, that large atomic size mismatch, which give distortions, also hinders the very formation of single phase alloys.

We are opening a theoretical design route to circumvent this problem through a high-pressure window to find alloys with large distortions that have previously been impossible to synthesize. The idea is to identify alloys with large lattice mismatch but where high or moderate pressure can force them into solid solutions. We are investigation both multicomponent alloys, so called high-entropy alloys, but also investigating binary and ternary systems where no alloys have been thought possible. The theoretical studies are followed up by high-pressure and thin-film deposition synthesis by our collaborators. Followed by property and stability characterizations.

[1] globalgoals.com; Passed by the UN General Assembly 25 Sept. 2015, Resolution A/RES/70/1.

[2] Swedish environ. protect. agency, Fördjupad analys av den sv. klimatomställningen 2019, p 26.

[3] Materials Genome Initiative for Global Competitiveness, NSTC, USA, June 2011.

Life in our planet is highly dependent on plants as they are the primary source of food, regulators of the atmosphere, and providers of a variety of materials. The climate crisis and population growth call for plants that are more resistant to biotic and abiotic stress in order to provide food security and healthy forests for carbon sequestration. At the same time a mechanistic understanding on how plants respond and acclimate to stress is lacking. While genetic engineering methods provide powerful tools in plant science, organic bioelectronic technologies can offer unique capabilities for real time monitoring and dynamic modulation of plant physiology and their stress responses that is the focus of this project. The project is therefore related to UN Sustainable Development Goals 2-Zero Hunger, 13-Climate Action and 15-Life on Land.

Specifically, we developed Organic Electrochemical Transistor (OECT) based implantable sensors for real-time monitoring of sugars variations in trees (Fig. 1A)1. Sugars are direct products of photosynthesis, being the main energy source in plants, but are also involved in plants stress responses. The OECTs sensors show high device-to-device reproducibility, stability during the operation in the in-vivo environment for over 48 hours and most importantly they do not cause a significant wound response from the plant. The sensors revealed previously uncharacterized sugars dynamics, highlighting the potential of this technology for elucidating sugar transport in plants (Fig. 1B). Furthermore, we demonstrated controlled delivery of phytohormone ABA, one of the main hormones involved in stress responses with the capillary-based Organic Electronic Ion Pump (OEIP), an electrophoretic delivery device 2. Currently, we are extending the OEIP mediated hormone delivery for controlling plants’ transpiration and developing feedback-regulated delivery based on temperature and humidity sensors for enhancing plants’ resistance to drought (Fig. 1C,D)3.

Figure 1: A. OECT sugar sensors inserted in the stem of Hybrid Aspen tree. B. Real-time response of sucrose sensor, glucose sensors, and control device for 48h in xylem tissue. C. OEIP inserted in Arabidopsis leaf petiole for in-vivo ABA delivery while LICOR is monitoring the stomatal conductance. D. Stomatal conductance of plants before and after OEIP-mediated ABA delivery  

References

1. “Diurnal in vivo xylem sap glucose and sucrose monitoring using implantable organic electrochemical transistor sensors” C. Diacci, T. Abedi, J. W. Lee, E. O. Gabrielsson, M. Berggren, D.T. Simon, T. Niittylä* and E. Stavrinidou* iScience, 24, 101966 (2021)
2. “Implantable Organic Electronic Ion Pump Enables ABA Hormone Delivery for Control of Stomata in an Intact Tobacco Plant” I. Bernacka-Wojcik, M. Huerta, K. Tybrandt, M. Karady, Y. Mulla, D. J. Poxson, E. O. Gabrielsson, K. Ljung, D. T. Simon, M. Berggren and E. Stavrinidou* Small, 1902189, (2019)
3. I. Bernacka-Wojcik, … E. Stavrinidou*, in preparation

Injuries, diseases and disorders of the peripheral nervous system represent a major challenge for society, as it is associated with common medical conditions such as neuropathic pain, loss of sensor- and motor function, and mis-regulation of organs. To develop treatments for these conditions with minimal side effects, peripheral nerve interfaces that selectively can access the thousands of fibers within a nerve are needed. Current high-density peripheral nerve interface technologies are limited by scar tissue formation around the probes due to the combination of bodily motions and the huge mechanical mismatch between the nerve tissue (elastic modulus ~20-200 kPa) and the flexible (~1 GPa) or stiff (~100 GPa) probes. Soft neural probes could resolve this issue, but to date there exist no soft inert high-performance conductive composite that can be miniaturized to the necessary extent (≤ 5 µm linewidth) to make such soft neural probes. Here, the aim is to resolve this material and processing challenge by developing tailor-made composites and processes for miniaturized biocompatible stretchable conductors. The novel strategy proposed here is to combine gold nanomaterials, for conductivity, with plasticized self-doped conjugated polyelectrolytes, to create a robust electrical percolative network at the micrometer scale.

The objectives of the proposed project are to develop:

• Novel miniaturizable soft conductors based on gold nanomaterials, plasticized self-doped conjugated polyelectrolytes, and elastomers (Figure 1).
• Processes which allow for fabrication of conductor linewidths of ≤ 5 µm on wafer-scale.
• A first prototype of an imperceptible neural probe.

Expected Results: Scientifically, the proposed project addresses a previously unexplored but key material aspects for the further development of soft neural interface technology; how to tune the percolation network on the nano- and micro-scale in soft conductors to allow for far reaching miniaturization. The proposed composites, fabrication methods, and applications are novel and expected to have a significant impact on the field. The project contributes to the UN Agenda 2030 sustainable development goal 3, good health and wellbeing, by developing novel materials and devices for biomedical applications.

Chronic non-healing skin wounds causes significant morbidity and mortality in affected patients and imbues a tremendous burden on the healthcare system, constituting one of the single largest healthcare budget posts in developed countries. Chronic wounds are susceptible to infection from a wide range of pathogens, which prevent healing and restoration of normal skin functions. About 40,000 patients in Sweden are treated for chronic wounds in local healthcare centers and up to 20,000 patients in hospitals. The chronification of wounds is mainly due to infection of pathogenic bacteria and biofilm formation, and to a larger extent by bacteria that are resistant to essentially all common antibiotics. The alarming increase in drug resistant bacteria combined with an aging population are currently accelerating the problems with non-healing wounds, leaving both patients and physicians with very few options. New strategies for inhibiting infections and supporting normal wound healing are consequently urgently needed.

In this project we develop nanocellulose-based composite materials for advanced wound care. We develop both materials that can facilitate early-stage detection of infections and materials that can deliver high local concentrations of novel potent antimicrobial compounds to combat persistent wound infections involving multidrug resistant bacteria. The materials are optimized to mimic structure and function of the skin and can stimulate healing by integrating into the wound microenvironment. We functionalize the nanocellulose materials with both mesoporous nanoparticles and drug eluting hydrogels. The novel composite materials are characterized using biophysical techniques and in different wound models with a clear translational ambition. In addition to wound care applications, the materials-fabrication strategies explored in this work can pave the way for development of a plethora of new advanced functional materials for applications in many other fields, including nanoplasmonics, water purification, and carbon capture.

The beautiful colours of stained glass appear thanks to metallic nanostructures embedded in the glass. This forms an ancient example of how metal nanostructures have been used as resonant antennas for light, which today is utilized in many different areas. Instead of conventional metals like gold or silver, our research explores organic conducting polymers as a new type of materials for such optical nanoantennas. The unique ability to repeatedly tune the conductivity of these materials opens for a new type of dynamically tuneable nanooptics,1,2 with future use in applications such as flat optics and energy-saving smart windows. We have so far managed to make systems tuneable by both chemical stimuli(1) and electrical potentials.(2)
In addition to optical nanoantennas, we also investigate conducting polymers in new types of optical cavities that provide tuneable structural colours, for example based on electrically triggered thickness changes.(3,4) Such systems may enable energy-efficient reflective displays and electronic readers in colour. 

Figure 1. (top left) Dr. Akchheta Karki and Prof. Magnus Jonsson discussing their electrically tuneable plasmonic conducting polymer nanodisk antennas.2 (top right) Structural colour image made by UV-patterning of a conducting polymer on a metal mirror.3 (bottom) Schematic and tuneable reflectance data for a dynamically tuneable optical cavity having a conducting polymer as spacer layer.4 Photos: Thor Balkhed, LiU.  

Popular science articles of this and related research:

https://liu.se/en/news-item/nanoantenner-for-ljus-kan-styras-elektriskt

https://liu.se/en/news-item/de-skapar-styrbara-plasmoner-i-plast

https://liu.se/en/news-item/fargskarmar-pa-nytt-satt-

https://fof.se/artikel/varde-nanoljus/

References:

1. Conductive polymer nanoantennas for dynamic organic plasmonics. S. Chen, E. S. H. Kang, M. S. Chaharsoughi, V. Stanishev, P. Kühne, H. Sun, C. Wang, M. Fahlman, S. Fabiano, V. Darakchieva and M. P. Jonsson. Nature Nanotechnology 2020, 15, 35–40
2. Electrical Tuning of Plasmonic Conducting Polymer Nanoantennas. A. Karki, G. Cincotti, S. Chen, V. Stanishev, V. Darakchieva, C. Wang, M. Fahlman and M. P. Jonsson. Advanced Materials 2022, doi:10.1002/adma.202107172, early view
3. Tunable structural color images by UV-patterned conducting polymer nanofilms on metal surfaces. S. Chen, S. Rossi, R. Shanker, G. Cincotti, S. Gamage, P. Kuhne, V. Stanishev, I. Engquist, M. Berggren, J. Edberg, V. Darakchieva and M. P. Jonsson. Advanced Materials 2021, 33, 2102451
4. Dynamically Tuneable Reflective Structural Coloration with Electroactive Conducting Polymer Nanocavities. S. Rossi, O. Olsson, S. Chen, R. Shanker, D. Banerjee, A. Dahlin and M. P. Jonsson. Advanced Materials 2021, 33, 2105004

Autonomous movement is an essential capability in living organisms. It allows the individual species to grasp and manipulate objects, as well as to move, to escape danger, find food, or meet other individuals. Nature has developed various means that enable movement and locomotion, from protein motors that drive cilia to specialised muscle tissue, all autonomous and self-powered. In mammalian muscles, glucose and oxygen (O₂) are consumed to generate adenosine triphosphate (ATP) by aerobic respiration. The ATP, being converted to adenosine diphosphate (ADP) due to hydrolysis, in turn drives the nanoscopic conformational changes in the myosin heads with respect to the actin filaments that cause the macroscopic muscle contraction and elongation. In contrast, human-made devices such as industrial or humanoid robots are typically driven by classical actuators that use electrical, pneumatic, or thermal actuation means and are often tethered or require large batteries. Driving soft actuators, or ‘artificial muscles’, directly using biofuels such as glucose, is highly anticipated. It would enable (soft) robotic devices to be fuelled by green, biofuels such as glucose, methane or alcohol. It would open possibilities for driving implants or injectable vehicles in the body without the need for batteries or external charging sources such as by radiofrequency (RF) coils.

Researchers have developed various soft, artificial muscles, e.g. based on dielectric elastomers and carbon nanotubes, but also made from fishing lines and textiles. However, they are still all powered by electrical or thermal means. Conducting polymers are very interesting materials to construct artificial muscles because they are driven at low potentials and provide a simple linear movement. They are based on an electrochemically induced volume change that occurs when ions and water enter or egress the polymeric material. This volume change has been used to build artificial muscles in various configurations such as a linear fibre and a so-called three-layer bending actuator. In the three-layer bending actuator, the conducting polymer, e.g. polypyrrole or poly (3,4-ethylenedioxythiophene, PEDOT) is coated on two sides of a flexible membrane. When a potential difference is applied between the two conducting polymer layers, the conducting polymer on the one side will be electrochemically oxidized and the conducting polymer on the other side will be reduced. This causes one layer to shrink while the other swells, resulting in a bending motion. However, even these artificial muscles are still driven by an external, often tethered, electrical power source. A direct conversion of chemical energy into electrical energy to power these biomimetic machines would be an elegant solution.

Schematic of the enzyme embedded CP actuator (left) and a photo of the resulting movement of the CP actuator powered by glucose and O2 only (right). Catalysts such as enzymes can achieve such direct conversion and would capitalise on the efficiencies already achieved by nature. Enzymes are used today e.g. in bioelectrodes. Coupled as a pair, such bioelectrodes can form a biofuel cell that can generate an electrical potential from biofuels. Bioelectrodes that convert glucose and oxygen, respectively, are particularly interesting because they enable to generate electrical potential from physiological fluids as glucose, which is present in all organs. This means that there is no need to pump fuel. Oxygen is also present in all organs, which removes the need to supply air through a membrane into the cathode chamber. Glucose as a biofuel has e.g. been used to power pacemakers. Despite these advances in biofuel cells, artificial muscles are still powered by external power sources.

In this project we want to develop soft actuators, or artificial muscles, which like the muscles of mammals, are driven by glucose and oxygen. This is achieved by developing hybrid materials where enzymes are integrated into conducting polymers. In this way, chemical energy can be directly converted into mechanical motion. The new hybrid material will be demonstrated in various soft actuators.

https://liu.se/en/news-item/konstgjorda-muskler-som-drivs-av-glukos

Thin layers, or films, of materials are essential in most areas of modern technology. The electronics in our computers and smartphones are made from layers of several films with carefully controlled electrical properties. One of the most important techniques to deposit these films is chemical vapor deposition (CVD) which uses chemical reactions between molecules containing the atoms needed for the material to deposit the film. My group has recently invented a new CVD method1 where we use the free electrons in a plasma for chemical reactions on the surface where the film is desired.

This far we have used the new CVD-method to deposit metals, In the first part of this project we seek to take the CVD-method to the next level and develop deposition of the semiconductors silicon and germanium. Then in the second part of the project we will utilize the inherent area-selectivity of the CVD-method, that it only deposits on low resistivity areas, and use nanometer-wide low resistivity areas to deposit nanometer-wide films of silicon and germanium.

Nanometer wide structures of silicon or germanium form the basis for modern FinFET (Fin Field Effect Transistor) technology, used in the processors in all computes and smart phones. But today these structures are made by a very complicated multi-step etching process, in a top-down approach.

By developing an area-selective deposition process for these structures they can be made by a bottom-up approach instead.

A bottom-up approach is always more sustainable than a top-down approach since all atoms etched away in a top-down approach are treated as waste. The envisioned bottom-up process to the semiconductor nanostructures will replace a 20i-step etching process by a single-step deposition process. This reduction of processing steps will reduce the need for gases, electricity, and clean water in the fabrication of semiconductor chips, leading to more sustainable manufacturing of electronics, aligning the project with the Green Fab initiative launched by fab equipment maker Applied Materials.2

The low process temperatures and lower use of dependence on molecular species in our new CVD method means that our new CVD method is a form of Green CVD3. Thus, this project will address the UN-sustainability goals4 Industrial Innovation (goal 9) and Responsible production (goal 12)and reduction of clean water consumption in semiconductor fabrication, relevant to Clean Water (goal 6). In the longer perspective will the research in this project pave the way to Clean Energy (goal 7).

 

¹ Nadhom et al. J. Vac. Sci. Technol. A 2020 38, 033402.
² https://www.appliedmaterials.com/company/news/press-releases/2020/07/applied-materials-charts-a-course-for- enabling-a-more-sustainable-company-industry-and-world

³ Pedersen et al. J. Vac. Sci. Technol. A 2021, 39, 051001.
⁴ https://sdgs.un.org/goals

The purpose of the project is to develop and apply a new methodology for systematic theoretical search of stable solids with dynamic disorder that can be suitable for applications related to UN Agenda 2030, sustainability goal #7 (access to affordable, reliable, sustainable and modern energy for all). Dynamically disordered solids (see Fig.1 for examples) are those with no well-defined time- averaged atomic positions of one of constituting elements. They can, in particular, provide anomalously large ionic conductivities, ultralow thermal conductivity, and transition temperatures to a superionic state, which can be tuned by an external stress field. Therefore, the direct applications are superior electrolytes in solid-state batteries and solid oxide fuel cells (SOFC), thermoelectrics, and mechanocaloric materials. Stability of dynamically disordered solids is the biggest issue, which cannot be addressed by standard theoretical methods. The project employs our recently developed method with AFM support that predicts stability of dynamically disordered systems (see https://liu.se/en/news-item/teorierna-avslojar-de-oordnade- fasta-materialen) and moves in the direction of dramatic increase of its feasibility for high-throughput search for new stable dynamically disordered materials. The expected results are a new method for fast and accurate description of phase stability in solids with strong anharmonicity and dynamic disorder; and high-throughput AI- assisted search for new stable dynamically disordered materials suitable for industrial applications. Figure 1. Schematic view of dynamically disordered phases. (a) Snapshot of a defective fluorite structure of δ-Bi2O3 (fastest known solid oxide ion conductor). Well defined ordered face-centered cubic (fcc) Bi sublattice (magenta). Heavy disorder among O ions (red balls), “liquid-like” diffusion. (b) Ordered tetragonal β-Bi2O3. (c) Cubic antifluorite structure of Li2C2 (a potential battery material). Well defined ordered simple cubic (sc) Li sublattice (grey). Rotational disorder of C2 – dimers is illustrated with red blobs. (d) Orthorhombic, low-temperature phase of Li2C2 with C2 – dimers aligned along the b axis.

This project addresses the issue of efficient energy and resource consumption in industrial processes, which has been defined by United Nations as one of the sustainable development goals. We use our expertise in physical vapor deposition (PVD) to develop new processing routes for production of functional coatings on cutting tools with significantly reduced power consumption (eco-PVD).

An important advantage of PVD technology is that it is more environmentally friendly than tradi-tional coating processes such as electroplating or chemical vapor deposition. PVD is clean and dry, with no hazardous materials, and does not generate chemicals. Nevertheless, PVD consumes large amounts of energy. This is primarily due to the fact that most coatings are deposited at elevated temperatures, Ts/Tm > 0.3 (Ts and Tm: growth and melting temperatures in K) corresponding to Ts > 900 °C for TiN to ensure sufficient adatom mobility. Films grown with no external heating are un-derdense (see Fig. 1(a)-(c)) and exhibit poor mechanical and optical properties with high resistivity. The classic solution is to employ gas-ion (e.g., Ar+ and N2+) bombardment to densify the films. This allows for lowering Ts to 400-500 °C at the expense of higher compressive stress, due to significant concentrations of trapped gas atoms, which is highly undesired as it results in cohesive film failure and delamination. As a consequence, typical PVD process requires hours of system preheating and intense cooling to protect temperature-sensitive components. For example, a research system in our laboratory uses 20 kW with a cooling water flow of 100 l/min.

Our approach relies on the paradigm-changing idea of replacing the conventionally used ther-mal energy flux from resistive heaters with the irradiation by high mass metal ions, which results in more efficient energy transfer to the deposited layer. Project capitalizes on recent advances in the field of magnetron sputtering such as high-power impulse magnetron sputtering (HiPIMS), which serves as the source of metal ions. The metal-ion mass, incident flux, and impact energy can be independently and synchronously controlled in our novel hybrid HiPIMS/DCMS deposition sys-tem. , , ,

Preliminary results using Ta+ metal-ion irradiation during low-Ts DCMS growth (< 120 °C, see SEM images in Fig. 1) reveal dramatic effect on the film microstructure. Extreme porosity in reference TiN (Fig. 1(a)) and Ta-DCMS Ti0.41Al0.51Ta0.08N (Fig. 1(c)), characteristic of low-Ts growth, is evident and results in poor mechanical properties. With pulsed Ta+ ion irradiation, inter- and intracolumnar porosity is eliminated (Figs. 1(b) and 1(d)). Film hardness depends on the incident Ta+ energy and is 330 % higher than for the reference DCMS layers, while the residual stress is low.4,5

The ultimate project goal is 50% reduction of power consumption by completely eliminating sub-strate heating requirements. Additional benefits include (i) improved PVD economics due to short-er operational cycles as heating/cooling times are eliminated, and (ii) the ability to coat on temper-ature-sensitive substrates.

Towards environment-friendly physical vapor deposition (eco-PVD) of advanced functional coatings and better understanding of heavy-metal-ion/surface Fig. 1 XSEM images showing the effect of metal ion bombardment on the nanostructure of TiN and TiAlN films grown with no external heating (Ts < 120 °C). TiN (a) and TiAlTaN (b) films grown with DCMS show extremely open columnar structure characteristic of a low Ts growth. In contrast, TiTaN (c) and TiAlTaN (d) layers grown with synchronous 160 eV Ta+ bom-bardment from HiPIMS target are fully dense with only 4 at% Ta added.

V. Kouznetsov, K. Macak, J.M. Schneider, U. Helmersson and I. Petrov, Surf. Coat. Technol. 122 (1999) 290
G. Greczynski, I. Petrov, J.E. Greene, L. Hultman, J. Vac. Sci. Technol. A 37 (2019) 060801
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G. Greczynski, J. Lu, I. Petrov, J.E. Greene, …, L. Hultman, J. Vac. Sci. Technol. A 32 (2014) 041515
H. Fager, …., J. E. Greene, L. Hultman, I. Petrov, G. Greczynski, J. Appl. Phys. 121 (2017) 171902

Contact Principal Investigator:
Grzegorz Greczynski

The evolution of electronics, from the room-size ENIAC computer to the compact and portable smartphones, had been revolutionizing our daily life. However, recent innovations in the field of electronics have been making devices even more versatile, wearable, and even skin-like. Various electronic skins, such as sweat sensors for health monitoring and tactile sensors for soft robotics, have already been demonstrated based on the development of electron conducting elastomers and/or ion conducting elastomers. Nonetheless, mixed ion-electron conductors, a vital component for many electrochemical devices and advanced bioelectronics, are yet to be transformed into conducting elastomers.

This project aims to develop mixed ion-electron conducting elastomers by using low-cost, biocompatible, and solution-processible organic materials. By combining different materials in nano- and micro-scales via solution process, a composite that possesses ion conduction, electron conduction, and skin-like mechanical properties will be formed. Conducting polymers and polyelectrolytes are of special interest since they can have multifunctionality in themselves, i.e., mixed ion-electron conduction in conducting polymers, and ion conduction with soft polymeric network in polyelectrolytes. The development of such a material platform will enable the exploration of charge dynamics and structure-property relations of mixed conductors owing to the strain-induced morphological changes and the fine-tunability of properties achievable by controlling compositions. Moreover, the development of mixed ion-electron conducting elastomers will allow for safe, stable, skin-like wearable and implantable devices for bioelectronics (neural electrodes, electrochemical sensors), artificial muscles (electrochemical actuators), displays (electrochromic displays, light-emitting electrochemical cells), and power sources (batteries, supercapacitors).

A solution-processed, mixed ion-electron conducting elastomer that allows for safe, stable, skin-like wearable electrochemical devices.

Contact Principal Investigator:
Nara Kim

Catalysis, drug delivery, and sensing are just some of the applications benefiting from the usage of mesoporous materials. Mesoporous particles and films have pores in the range of 2 – 50 nm, giving the materials a specific surface area of more than 500 m2/g. Optimization of the material’s pore characteristics and stability is crucial for its performance, for example to control the drug release profile, or the diffusion of reagents and product during catalysis, and hence knowledge of the material formation is vital. This project builds on a new method to synthesize particle-based mesoporous films, and aims to reveal the interactions between micelles, silica species, and substrates to form materials with controlled characteristics in terms of silica structure and porosity. The film synthesis method enables a homogeneous film growth on non-flat substrates and can be grown on for example medical implants and metal foams.

To reach the project goal, in situ and ex situ experimental techniques are combined with theoretical modelling to monitor the formation of mesoporous silica and predict how variations in the synthesis parameters affect the material characteristics. The mesoporous particles and films will be used as drug carriers, and the drug release profile will be correlated with the material structure. The results from this project will yield a significant step for the ability to tailor mesoporous materials for drug delivery applications where the drug release can be controlled over long times. The results can also be used for material design in other fields, such as catalysis and sensing.

Figure 1. SEM micrographs of top view and cross sections of mesoporous silica films with different particle sizes due to altered NH4F concentrations during the material synthesis. [1] Figure 1. SEM micrographs of top view and cross sections of mesoporous silica films with different particle sizes due to altered NH4F concentrations during the material synthesis. [1]
Figure 1. SEM micrographs of top view and cross sections of mesoporous silica films with different particle sizes due to altered NH4F concentrations during the material synthesis. [1]

[1] Cell adherence and drug delivery from particle based mesoporous silica films
E.M. Björk, B. Baumann, F. Hausladen, R. Wittig, and M. Lindén

Contact Principal Investigator:
Emma Björk

Neurodegenerative diseases and neuronal disorders represent a considerable social and economic burden of aging societies. While the understanding of their origins and mechanisms is advancing, effective treatments are still elusive. Current approaches, relying on biochemical methods, face limitations and a growing need for innovative strategies. Electrical wiring of cells: traditional metal contacts vs. in-situ manufactured organic electronic pharmaceuticals. Electroceuticals, utilizing electrical impulses to modulate neural circuits in the body, offer a promising avenue. Electrodes are used to mediate communication between the body and electronics, enabling stimulation for growth and differentiation, recording of signals for diagnostics, and monitoring of tissue activity. However, conventional metal electrodes can trigger an immune response, leading to scar tissue formation and compromised communication. In contrast, conductive polymers, being soft and biocompatible, present an attractive alternative. Because of their unique ability to transport both ions and electrons, conductive polymers are ideal candidates to bridge the electronic-biology gap and to interface biological systems like the human brain. The latest frontier in this realm is the exploration of organic electroceuticals, organic electronic devices, manufactured in vivo within the nervous system. Despite this exciting prospect, there remains a significant knowledge gap regarding how these materials interface with biological systems at the single-cell and nanoscale levels.

The goal of this project is to unravel the mechanisms governing the electroactive polymer-cell membrane interactions and to derive relevant methods to control them. Conductive polymers will be assembled on cell membranes by enzymatic polymerization with the use of membrane anchors. Advanced beyond-imaging protocols, based on scanning probe microscopy, will allow to derive relevant nanoscale structure-property relationships on the model systems, by correlating their morphology with the mechanical, electrical and electrochemical properties. The behavior of the cell-polymer interface when electrically stimulated, i.e. when the polymer layer is switched between its doped and undoped form, will be assessed.

This comprehensive investigation seeks to provide fundamental knowledge crucial for the development of in vivo-fabricated organic electroceuticals, opening new avenues for symptom suppression and therapy of targeted disease in the future

Contact Principal Investigator: Chiara Musumeci