Efficient perovskite solar cells with low J-V hysteretic behavior based on mesoporous Sn-doped TiO2 electron extraction layer

Organic-inorganic halide perovskite solar cells (PSCs) have recently become a promising and potentially commercially-ready photovoltaic device. However, the hysteresis effect is one of the most significant problems hindering this progress. The main reasons can be attributed to the lower electron mobility of TiO2, causing the imbalance of electron and hole flux. The shallow trap states close to the conduction band are formed by oxygen vacancy, leading to charge recombination. Therefore, elements doping is a valuable strategy for improving electron properties and passivating defects. Herein, we proposed Sn as a dopant in mesoporous structure TiO2 (meso-Sn:TiO2), causing the conduction band minimum and valence band maximum to be slightly upward shifted. The defect states decreased, and the carrier extraction improved. The PSCs with meso-Sn:TiO2 electron extraction layer improved the power conversion efficiency from 16.86% to 20.55%, enhanced the fill factor from 76.62% to 81.72%, and reduced hysteresis index from 0.16 to 0.03. This study proves that the Sn dopant is an effective strategy to improve the photovoltaic performance of PSCs.

Automated summary

Organic-inorganic halide perovskite solar cells have great commercial potential, but the hysteresis effect is a major issue. Doping Sn into TiO2 can improve electron properties and defect passivation, resulting in enhanced photovoltaic performance of PSCs.