Efficient Tin Perovskite Solar Cells via Suppressing Autoxidation in Inert Atmosphere

The unsatisfactory power conversion efficiency (PCE) and long-term stability of tin perovskite solar cells (TPSCs) restrict its further development as alternatives to lead perovskite solar cells (LPSCs). Considerable research has focused on the negative impacts of O2 and H2O, while discussions about degradation mechanism in an inert atmosphere remains insufficient. Herein, the light-induced autoxidation of tin perovskite in nitrogen atmosphere is revealed for the first time and the elastic lattice distortion is demonstrated as the crucial role of rapid degradation. The continuous injection of photons induces energy transfer from excited A-site cations to vibrating Sn-I framework, leading to the elastic deformation of perovskite lattice. Consequently, the over distorted Sn-I framework releases free iodine and further oxidizes Sn2+ in the form of molecular iodine. Through an appropriately designed light-dark cyclic test, a remarkable PCE of 14.41% is achieved based on (Cs0.025(MA0.25FA0.75)0.975) 0.98EDA0.01SnI3 solar cells, which is the record of hybrid triple TPSCs so far. The findings unveil autoxidation as the crux of TPSCs' degradation in an inert atmosphere and suggest the possibility of reinforcing the tin perovskite lattice towards highly efficient and stable TPSCs. Autoxidation of tin perovskites induced by elastic lattice distortion is revealed under illumination. The energy transfer from excited MA/FA cations to vibrating SnI bonds causes the deformation of Sn-I framework. As a result, iodine molecules are formed due to the fracture of SnI bonds, and further, lead to the oxidation of tin perovskites in nitrogen atmosphere.image

Automated summary

This study reveals the light-induced autoxidation of tin perovskite in nitrogen atmosphere for the first time, demonstrating the crucial role of elastic lattice distortion in rapid degradation. Through an appropriately designed light-dark cyclic test, a remarkable power conversion efficiency is achieved.