Decreasing energy loss and optimizing band alignment for high performance CsPbI3 solar cells through guanidine hydrobromide post-treatment

Abstract

On account of their superior thermal stability and applicable band gap (∼1.7 eV), the inorganic halide CsPbI₃ perovskite solar cells (PSCs) have aroused intense interest in recent years. Nevertheless, the CsPbI₃ PSCs still face a problem of high energy loss (E_loss) which leads to low open-circuit voltage (V_OC). Herein, we developed efficient CsPbI₃ PSCs through guanidine hydrobromide (GABr) post-treatment on the surface of CsPbI₃ films. After optimizing, a supreme power conversion-efficiency (PCE) of 18.02% was obtained, which was higher than the original one (16.58%). By further studying, the characterization of passivation was found, which led to a reduced nonradiative recombination rate. Besides, the band alignment between CsPbI₃ and the interface layer was also optimized, leading to the decreased electron transport barrier for electron collection, and superb hole contact for furnishing a driving force in the hole transfer and preventing electrons from flowing in the opposite direction.