Reducing the Schottky Barrier by SnS2 Underlayer Modification to Enhance Photoelectric Performance: The Case of Ag2S/FTO

The transfer and recombination of photoinduced charge carriers play the crucial roles in a photoelectric conversion system. In this work, the Ag2S/fluorine-doped tinoxide (FTO) was used as the platform to understand the photoinduced charge carrier transfer and recombination at the light absorber and electrode interface. SnS2 was evaporated onto the FTO surface to cooperate the Fermi level with Ag2S, which reduced the Schottky barrier at the Ag2S/FTO interface. Kelvin probe force microscopy measurements reveal that the Fermi level of FTO can be tuned from −4.93 to −4.75 eV by various SnS2 with different evaporation amounts. Transient surface photovoltage tests confirm that the recombination of the photogenerated charge carrier can be drastically suppressed. The photoelectric conversion efficiency of the resulting solar cell devices has been significantly improved.