Efficient Passivation Strategy on Sn Related Defects for High Performance All‐Inorganic CsSnI3 Perovskite Solar Cells

• Published in: Advanced functional materials Vol. 31; no. 11
• Main Authors: Li, Bo, Di, Haoxiang, Chang, Bohong, Yin, Ruiyang, Fu, Lin, Zhang, Ya‐Nan, Yin, Longwei
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.03.2021
• Subjects: Carrier lifetime; Carrier recombination; Commercialization; Crystal defects; CsSnI 3; deep level defects; Defects; Density; Electron clouds; Energy conversion efficiency; Free energy; Functional groups; Grain boundaries; Heat of formation; Lead; Materials science; Oxidation; Passivity; Perovskites; Photovoltaic cells; Sn vacancy; Solar cells; Surface defects; surface passivation; Tin; vapor deposition
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202007447

Despite remarkable progress in hybrid perovskite solar cells (PSCs), the concern of toxic lead ions remains a major hurdle in the path towards PSC's commercialization; tin (Sn)‐based PSCs outperform the reported Pb‐free perovskites in terms of photovoltaic performance. However, it is of a particularly great challenge to develop effective passivation strategies to suppress Sn(II) induced defect densities and oxidation for attaining high‐performance all‐inorganic CsSnI3 PSCs. Herein, a facile yet effective thioamides passivation strategy to modulate defect state density at surfaces and grain boundaries in CsSnI3 perovskites is reported. The thiosemicarbazide (TSC) with SCN functional groups can make strong coordination interaction with charge defects, leading to enhanced electron cloud density around defects and increased vacancy formation energies. Importantly, the surface passivation can reduce the deep level trap state defect density originated from undercoordinated Sn2+ ion and Sn2+ oxidation, significantly restraining nonradiative recombination and elongating the carrier lifetime of TSC treated CsSnI3 PSCs. The surface passivated all‐inorganic CsSnI3 PSCs based on an inverted configuration delivers a champion power conversion efficiency (PCE) of 8.20%, with a prolonged lifetime over 90% of initial PCE, after 500 h of continuous illumination. The present strategy sheds light on surface defect passivation for achieving highly efficient all‐inorganic lead‐free Sn‐based PSCs. A facile yet effective thioamides passivation strategy is proposed to suppress defects at the surface and grain boundary of CsSnI3 perovskite, which reduces the deep level trap density from undercoordinated Sn2+ and Sn2+ oxidation. The surface passivated CsSnI3 perovskite solar cell (PSC) delivers a efficiency of 8.20% which is the highest among all lead‐free all‐inorganic PSCs.