Interface Recombination of Cu2ZnSnS4 Solar Cells Leveraged by High Carrier Density and Interface Defects

Kesterite Cu2ZnSnS4 (CZTS) solar cell has emerged as one of the most promising thin-film photovoltaic technologies that allows for cheap, clean, and efficient renewable power in the future. Nevertheless, limited by the large photovoltage deficit caused by severe interface recombination, the potential of CZTS solar cells is far from being fully tapped. Herein, it is demonstrated that the carrier density of the CZTS absorber and the acceptor-like interface defects are two critical factors governing the interface recombination in addition to the unfavorable conduction band alignment. Results of device simulation suggest that passivating the acceptor-like interface defects combined with appropriate absorber carrier density is the essential way to promote the photovoltage and efficiency of CZTS solar cells to a more competitive level. It is believed that these results could be generally applicable to the interface recombination of other heterojunction solar cells.