Tuning hot carrier transfer dynamics by perovskite surface modification

Understanding the role of perovskite surface passivators in hot carriers transfer dynamics is important to develop highly efficient perovskite solar cells (PSCs). In this work, we have designed and synthesized a naphthalimide-based organic small molecule (NCN) for perovskite surface defect passivator. We reveal that the introduction of NCN not only reduces the density of perovskite defect-state, but also promotes hot carriers (HCs) cooling in perovskite through the transient absorption spectroscopy measurements. Fast HCs cooling permits HCs transfer from perovskite layer into NCN layer, thus resulting in the decreased charge-carrier recombination in NCN-treated device. As expected, the power conversion efficiency (PCE) of PSCs with NCN is enhanced to 22.02% from 19.95% for the control device. The findings are relevant for developing highly efficient PSCs.