Optoelectronics

Solar cell and perovskites
Olov Planthaber

We are a multidisciplinary team focusing on solution-processed optoelectronic devices, with a passion for both fundamental science and new applications of these materials and devices.

Optoelectronic devices, such as light-emitting diodes (LEDs), solar cells, photodetectors, lasers and optical transmitters and receivers, are an important part in maintaining a sustainable world. The emergence of exceptional solution-processed semiconductors, including organic semiconductors and metal halide perovskites, offers great opportunities for developing new generations of optoelectronic devices that are of high performance, cost-effective, and integrable with other technological systems.

We have developed a worldwide professional network for collaborations and are also actively engaging in collaborations with industry partners.

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Organic semiconductors

Organic semiconductors have a large potential in low-cost and large-area device applications, benefiting from cheap manufacturing processes such as solution-based roll-to-roll printing.
All device applications previously dominated by inorganic semiconductors have presented opportunities for their organic counterparts. Such applications include solar cells, LEDs, field-effect transistors, lasers, and memory devices.

 

Metal halide perovskites

Metal halide perovskites have emerged as one of the most popular semiconducting materials since 2009. They have shown unique properties, including:

• Tunable bandgap

• High absorption coefficient

• Broad absorption spectrum

• High charge carrier mobility

• Long charge diffusion lengths

These properties enable metal halide perovskites to be used in a broad range of photovoltaics and other optoelectronic applications.

 

Lead free perovskites /Lead free metal halides

The state-of-the-art perovskites used in optoelectronics contain toxic lead (Pb). Focus is therefore set on creating lead free perovskites or perovskite alike materials with as good properties as the lead containing. Lead can for example be exchanged to cupper (Cu), Iron (Fe), Manganese (Mn), and many other metals. Some of the ways of changing the properties of an optoelectronic material is modify the material composition, use additives or by changing the structural or the particle dimensionality.

 

Transport materials

The electron and hole transport layers are crucial for a device to work efficient and plays an important role in the degradation of the device. The group is using a large variety of transport materials, but an extra focus is set on improving a hole transport material group called spiro materials.

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Organic solar cell with the aktive layer Pm6:Y6Organic solar cell with the aktive layer Pm6:Y6 Photo credit Olov PlanthaberSolar cells

Although the current solar cell market is dominated by silicon-based devices, the recent emergence of solution-processed solar cells based on organic semiconductors and metal halide perovskites has shown great potential for commercial applications. For example, the power conversion efficiency of perovskite solar cells has soared from a few percent to over 25% within the past few years. Such a quick development has never been seen in the history of photovoltaics before.
 

Perovskite quantum dotsPerovskite quantum dots Photo credit Olov PlanthaberLEDs

LEDs, which emit light by a solid-state process called electroluminescence, are considered the most promising energy-efficient technologies for future lighting and displays. Metal halide perovskites demonstrate strong photoluminescence and tunable emission energy, making them a promising candidate for the next generation of highly efficient LEDs.

A combined optical transmitter and receiverA combined optical transmitter and receiver Photo credit Magnus JohanssonOther devices

Lasers are amplified coherent light with a variety of applications from communication to cutting tools or scientific instruments. Photodetectors and optical transmitters and receivers can for example be used in sensors found in smartphones and medical measurement tools. The group mostly focuses on solar cells and LEDs but some research is also conducted regarding lasers, photodetectors and optical transmitters and receivers.

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Research

The Optoelectronic group lead by Prof. Gao dedicates its efforts to energy devices, with the ambition to both improve device performance and understand the underlying fundamentals. Their current investigations include organic semiconductors and metal halide perovskites, with research focuses such as:

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2021

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Two male scientists walks and talks in a hallway.
Principal research engineer Weihua Ning and professor Feng Gao at the Department of Physics, Chemistry and Biology. Thor Balkhed

Group and Supervision

Prof. Feng Gao is deeply involved in both the scientific and career development of his group members. The senior researchers in his group have been awarded the prestigious VR Staring Grant, Marie Skłodowska-Curie Individual Fellowship, VINNMER Fellowship.

He also values the exchange of ideas: he has sponsored members of his group in exchanges to Cambridge, Oxford and EPFL, and his group has hosted visiting students and scholars from Cambridge, Zhejiang University, Nanjing University, Nanjing Tech University, Shenzhen University, Queen Mary University of London, and more.

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