Para-Substituent Effects on Interfacial Binding and Fast Hole Transfer Dynamics in CsPbBr₃ Nanocrystals for Perovskite-Based Photocatalysis

In solar energy conversion and photocatalysis, lead halide perovskite nanocrystals (LHP NCs) have emerged as highly promising materials due to their unique nanoscale optoelectronic properties, including high absorption coefficients, long carrier diffusion lengths, and tunable bandgaps. However, a critical challenge in photocatalytic applications lies in the efficient extraction of photogenerated charge carriers from these NCs before recombination occurs, which directly impacts their catalytic efficiency. Among various factors, the strength of interfacial interactions between the nanocrystals and charge-accepting molecules plays a pivotal role in enabling ultrafast and directional charge transfer, crucial for driving surface redox reactions. The influence of para-substituents on the anchoring groups has not received much attention, despite the fact that different anchoring functional groups have been thoroughly investigated to understand these relationships. To address this gap, we systematically investigated how these para groups affect the interfacial binding and charge transfer kinetics of LHP NCs using hole-accepting molecules (HAMs) that have different para-substituents but a common anchoring group. Six para-substituted aniline derivatives with distinct para-substituents but the same amine (–NH 2 ) anchoring group were specifically selected as HAMs for this study to investigate their interactions with CsPbBr 3 perovskite NCs. Our findings demonstrate a direct relationship between interfacial binding and charge transfer efficiency, showing that the association constant ( K a ) and the hole transfer rate ( k ht ) both rise with the para-substituent’s electron-donating strength. These findings underscore the critical role of nanoscale interfacial engineering in advancing perovskite-based photocatalytic systems and provide valuable insights for the rational design of surface-binding hole acceptors. By tailoring side-chain substitution, one can fine-tune interfacial energetics and optimize the photocatalytic performance.