Binary Selenide (Sb2Se3 and CdSe) Thin-Film Solar Cells

With the continuously increased efficiency and reduced cost, silicon solar cells strengthen their dominance in the market. To be realistic, the emerging inorganic thin-film photovoltaics need either possess novel functionalities to complement silicon solar cells, or ally with silicon to make it even stronger. In this presentation, I will briefly report on the research done in our group. For antimony selenide (Sb2Se3), it has a one-dimensional (1D) crystal structure so making it scientifically interesting. When properly aligned via the judicious selection of substrate and optimization of deposition procedure, Sb2Se3 solar cells enjoy intrinsically benign grain boundaries and ultrahigh flexibility. With the assistance of a thin polyimide substrate, our Sb2Se3 solar cells shows outstanding flexibility: when bent with only 0.1 mm radius for 500 cycles, the efficiency degradation is 2%, a metric impossible for silicon solar cells. For CdSe, it has a band gap of 1.7 eV and could be deposited at <500 C, enabling the integration with silicon solar cells to build a tandem device. Using a thermal evaporation method and employing a PIN device structure, our CdSe solar cell has achieved a power conversion efficiency of >6%, showing its potential for further optimization as the top cell for next-generation silicon tandem devices.