Interface Chemistry as a Gatekeeper for Charge Transfer in Perovskite Photocatalysts

Organic synthesis driven by lead halide perovskite-based photocatalysts has emerged as a powerful route for advanced chemical transformations, propelled by their remarkable light-harvesting capability and efficient charge generation. Among the various factors influencing their activity, charge-transfer dynamics at the nanocrystal–molecule interface dictates the photocatalytic efficiency. Yet, the impact of surface termination on charge transfer with molecular hole acceptors represents a significant knowledge gap, especially in formamidinium lead bromide (FAPbBr3) nanocrystals. Here, we uncover how ferrocene-functionalized hole acceptors, ferrocenecarboxylic acid (FcA) and (dimethylaminomethyl)ferrocene (FcAm), interact distinctly with FAPbBr3 and CsPbBr3 nanocrystals, revealing the critical influence of surface chemistry on charge-transfer pathways. Comprehensive photophysical investigations show that both the molecular functionality of the acceptor and the surface termination of the nanocrystal jointly dictate the interfacial charge-transfer behavior. While FcA is energetically well-aligned, it fails to extract holes from FAPbBr3 nanocrystals due to the absence of accessible Pb2+ binding sites. In contrast, protonated FcAm efficiently extracts holes by engaging the vacant FA+ sites on the nanocrystal surface. Time-resolved measurements further confirm that this hole transfer originates from band-edge states rather than hot carriers. CsCl doping experiments substantiate the role of surface termination, as doping effectively suppresses charge transfer to FcAm. Overall, these findings establish surface termination as a key determinant of interfacial charge transfer in perovskite–molecule hybrid systems. They further highlight cation engineering as a powerful approach to tune surface energetics and improve photocatalytic efficiency, providing valuable design principles for next-generation perovskite photocatalysts aimed at overcoming interfacial charge-transfer bottlenecks.