Achievable high Voc of carbon based all-inorganic CsPbIBr2 perovskite solar cells through interface engineering

Abstract

In this work, a simple interface engineering process for SnO₂ electron selective layer (ESL) surface passivation employing a SnCl₂ solution is introduced, which has successfully reduced the energy loss for a high open-circuit voltage (V_oc) output and consequently improved the performance of all-inorganic CsPbIBr₂ perovskite solar cells (PSCs). It was found that surface passivation can effectively suppress the recombination process at the interface between the perovskite and SnO₂ due to higher recombination resistance. The shorter PL decay time is attributed to the excellent electron extraction from the perovskite film. After optimizing surface passivation, the power conversion efficiency (PCE) was enhanced from 4.73% to 7.00% and a high V_oc of 1.31 V was achieved, which is one of the highest V_oc values reported for inorganic Cs-based PSCs. More importantly, the passivated SnO₂ based device retains 95.5% of its initial performance at 90 °C in air without encapsulation. This work provides a simple and efficient interface engineering method to improve the V_oc and efficiency of all-inorganic PSCs.