Probing Interfacial Charge Transfer across the Perovskite Nanocrystal and Band-Aligned Electron Transport Material

The efficiency of perovskite nanocrystals (P-NCs)-based optoelectronic devices is significantly influenced by charge transfer (CT) kinetics at the interface of active layer and electron- or hole-transporting layers. Our study explores the photoinduced CT from cesium lead bromide (CsPbBr3) P-NCs to zinc-oxide (ZnO) and titanium dioxide (TiO2) nanoparticles (NPs), highlighting its impact on enhancing photovoltaic device performance through combined spectroscopic, electrical, and theoretical analyses. We observe strong photoinduced interactions of P-NCs with these two NPs forming composites, with significant CT for TiO2 NPs than ZnO NPs, stemming from the more favorably aligned energy level of TiO2 with P-NCs. In line with the spectroscopic results, the conductive atomic force microscopy measurements discern a more plausible increase in the current conduction of P-NC in the presence of TiO2 NP. Theoretical simulations further reveal a performance boost for TiO2 compared with ZnO devices. These results underscore the importance of controlled interlayer CT in enhancing the photovoltaic device performance.