Interfacial Acceptor Binding As a Handle to Control Photocatalysis in Perovskite Nanocrystals

Carbon-carbon (C-C) bond formation via photoredox catalysis offers a sustainable route for organic synthesis, which often relies on noble-metal systems but is limited by rapid charge-carrier recombination. Here, we demonstrate an efficient photocatalytic strategy based on CsPbBr₃ nanocrystals interfaced with para-substituted aniline (PSA) molecules, in which interfacial binding is systematically tuned to control charge-transfer dynamics. By employing a series of PSA derivatives with varying electron-donating substituents, we modulate the association constant (K_a) and hole-transfer rate constant (k_ht) at the nanocrystal interface. This platform enables photoreductive C-C bond formation via the dimerization of phenacyl bromide under mild conditions, using CsPbBr₃/PSA photocatalysts. Importantly, we establish a direct correlation between photocatalytic yield, K_a, and k_ht, revealing that stronger interfacial binding promotes faster and more efficient hole extraction, suppresses recombination, and enhances catalytic performance. Despite minimal variation in HOMO energy levels among the PSA derivatives, significant differences in reaction progress are observed, underscoring that interfacial binding, rather than energy-level alignment alone, governs charge-separation efficiency. These findings highlight excited-state interfacial interactions as a key design principle for developing high-performance perovskite-based photocatalysts for solar energy conversion and photoredox applications.