Research

Assoc. Prof. Gao’s group dedicates its efforts to energy devices, such as solution-processed solar cells (see Highlight in Nature and paper in Nature Energy) and LEDs (see paper in Nature Photonics), 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:

• Fullerene-free organic solar cells
• Perovskite solar cells
• Perovskite LEDs
• Lead-free perovskites

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 photovoltaic and other optoelectronic applications.

Solar 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 20% within the past few years. Such a quick development has never before happened in the history of photovoltaics.

LEDs

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.

Funding

Assoc. Prof. Gao's research group is financially supported by the following funding agencies:

• European Research Council
• VR
• Vinnova
• Swedish Energy Agency
• Marie Skłodowska-Curie actions
• FORMAS
• The Wallenberg Foundations
• Swedish Energy Agency - Energimyndigheten

Group and Supervision

Assoc. Prof. Feng Gao is deeply involved in both the scientific and career development of his group members. Three senior researchers in his group have been awarded the prestigious VINNMER Marie Curie Fellowship. He also values the exchange of ideas: he has sponsored members of his group in exchanges to the universities in Oxford and Cambridge, and his group has hosted visiting students and scholars from Zhejiang University, Nanjing University, Nanjing Tech University, City University of Hong Kong, Queen Mary University of London, and more.