Unveiling Exciton-Molecular Crosstalk Mediating Photocatalysis on Perovskite Quantum Dots via <i>In-Situ</i> SERS

Semiconductor quantum dots (QDs) have emerged as a paradigm-shifting catalytic platform for visible-light-driven organic synthesis, owing to their highly tunable excitonic properties. However, the critical role of nanoconfined exciton evolution in governing surface reactions remains experimentally elusive. Here, we synthesized Au@perovskite QD superstructures for <i>in-situ</i> surface-enhanced Raman spectroscopy to probe exciton-molecular crosstalk during the photocatalytic self-coupling of aromatic thiols on QD surfaces. We find that quasi-ligand coordination of thiols with surface Pb sites simultaneously attenuates three exciton relaxation pathways: radiative recombination, Auger recombination, and exciton-phonon coupling, while enhancing trap-assistant recombination. Thermodynamically, coordinating molecules with varying substituent groups reduce the exciton binding energy (<i>E</i>_b) in QD systems through their tunable dipole moments. This excitonic modulation effectively lowers the activation barrier during the reaction and thus facilitates S-S bond coupling, as demonstrated by substituting -Cl with -OCH₃, which reduces <i>E</i>_b by 38.3% and increases the reaction rate by 84.7%. Our work reveals exciton-molecular crosstalk as a key mechanistic aspect in QD catalysis and enriches the theoretical framework of heterogeneous catalytic processes under quantum confinement.