Insight into the Importance of Charge Transfer Dynamics in CsPbBr₃ Perovskite Nanocrystals for Photovoltaic Applications

Charge transfer (CT) kinetics at the interfaces of lead-halide-based perovskite nanocrystals (PNCs) are pivotal in dictating the efficacies of energy conversion. Our investigation delves into the intricacies of CT between cesium lead bromide (CsPbBr3)-based PNCs and fullerene (C60) employing a suite of spectroscopic and theoretical investigations. Notably, we discern a facile interfacial photoinduced electron transfer (ET) from CsPbBr3 PNCs to C60, in good agreement with their respective aligned energy levels. Complementary current sensing atomic force microscopy measurements unveil a substantial enhancement in conductivity across the electrode–PNC–electrode nanojunction in the presence of C60. To establish the implications of such ET in photovoltaic devices, we have simulated the performance of two devices: one without C60 and one with C60. We unfold an impressive increment in the power conversion efficiency from 12.5% to 15.8% in FTO/CsPbBr3/PEDOT:PSS/Au configurations upon integrating a band-aligned C60 layer. These outcomes accentuate the relevance of regulated interlayer CT in optimizing photovoltaic device performance.