[16a-C41-1~6] New direction of perovskite solar cells

11:00 AM - 11:30 AM JST(2:00 AM - 2:30 AM UTC)English Presentation

[16a-C41-5] Stability of Tin Halide Perovskites – from Additives through Two-Dimensional Materials

〇Kenneth R Graham¹, Syed Joy¹, Tareq Hossain¹, Harindi Atapattu¹, Henry Pruett¹, Alex Boehm¹, Stephen Johnson² (1.Univ. of Kentucky, 2.Transylvania Univ.)

Keywords:

halide perovskite,solar cell,tin

Metal halide perovskites are promising materials for solar cells and light emitting diodes; however, the inclusion of Pb in the highest performing materials presents a potential barrier for their commercialization. The most promising alternative to lead-based halide perovskites (Pb-HPs) are those where Pb is substituted with tin (Sn-HPs). While Sn is much less toxic than Pb, the performance and stability of Sn-HPs must be improved for them to be competitive with Pb. The primary shortfall of Sn-HPs is the tendency of Sn to oxidize from Sn2+ to Sn4+. To increase both the PCE and stability of Sn-HPs, oxidization mechanisms must be understood, and appropriate processing and material chemistries developed. Our laboratory has focused on the use of surface ligands, stabilizing additives, and 2D Sn-HPs to determine how additives and 2D phases impact device performance, defects, and material stability. From the perspective of surface ligands, we find that fluorinated surface ligands and those that increase hydrophobicity lead to increases in material and device stability. In the case of additives, we find that additives which can coordinate Sn2+ or undergo halide exchange with SnI4 can limit Sn4+ formation and the concentration of defect states in the film. The acidity of the additive also exerts a large influence on stability, with more acidic additives promoting Sn2+ oxidation and basic additives stabilizing Sn2+. Recently, we have gained insight into the role the structure of the bulky ammonium cation plays in stabilizing 2D Sn-HPs. Here, we find that steric hindrance near the ammonium group, the extent of horizontally oriented sheets, and the degree of hydrophobicity all impact material stability.