Photoinduced Charge Transfer between Metal Halide Perovskite and Ru‐Polypyridyl Complexes Toward Biocatalytic Reactions

Abstract Vacancy‐ordered Bi‐based perovskites, such as Cs ₃ Bi ₂ Br ₉ (CBB), exhibit relatively high Lewis acidity due to Bi ³ ⁺ centers, providing favorable acidic sites for organic transformations. Coupled with their tuneable optoelectronic properties, these features render CBB an efficient photocatalyst for various acid‐catalyzed reactions. In this study, CBB is conjugated with a classical Ru(II)‐polypyridyl photosensitizer (RuPS) to form a hybrid material, CBB/RuPS, capable of facilitating thermodynamically favourable inner‐sphere electron transfer. This process yields the reduced RuPS radical anion (RuPS ^•− ) and a hole (h⁺) in the oxidized CBB species. Ultrafast charge recombination is suppressed through an efficient extraction of e− and h⁺ by the redox‐active substrates, generating spatially separated redox centres that drive tandem oxidative and reductive transformations. Comprehensive spectroscopic, microscopic, and analytical studies confirm the successful formation of the CBB/RuPS hybrid. Steady‐state and time‐resolved spectroscopic analyses reveal the thermodynamic viability of photoinduced electron transfer, with CBB exhibiting a sub‐nanosecond photoluminescence lifetime and electron transfer to RuPS occurring within 200–300 ps. This is evidenced by the appearance of RuPS ^•− signatures and multiexponential decay kinetics of CBB. Finally, the efficient exciton diffusion in the hybrid system is harnessed for in vitro photo‐biocatalytic reactions, enabling selective oxidation and reduction of substrates, demonstrating potential cytotoxicity toward cancer cells via deprivation of NADH/pyruvic acid and in situ generated ROS species.