Influence of Defects and Synthesis Conditions on the Photovoltaic Performance of Perovskite Semiconductor CsSnI3

Abstract

CsSnI3 is a prototype inorganic halide perovskite that has recently been proposed as a strong candidate for photovoltaic applications because of its unique semiconductor properties. Through first-principle calculations, we show that the concentration control of intrinsic defects is critical for optimizing the photovoltaic properties of CsSnI3. Under a Sn-poor condition, a high concentration of acceptor defects, such as Sn or Cs vacancies, can form easily and produce a high p-type conductivity and deep-level defects that can become electron–hole recombination centers, all with high energy. This condition is optimal for growing CsSnI3 as hole-transport material in solar cells. In contrast, when Sn becomes richer, the concentration of acceptor defects decreases; therefore, the p-type conductivity may drop to a moderate level, which can increase the shunt resistance and, thus, the efficiency of the solar cells with CsSnI3 as the light absorber material (LAM). However, under the Sn-rich condition, the concentr...