Quantum Dot-Induced Kinetic Bottleneck in Singlet Exciton Relaxation of Conjugated Polymer Aggregates

Abstract We designed hybrid aggregate model systems with cascade energy alignment from conjugated polymers (CPs) to quantum dots (QDs) to investigate the effects of QDs on CP singlet (S1) excitons. Radiative recombination of S1 excitons occurs within 1 ps in the chlorinated CP/QD hybrid system, indicating an enhanced emissive pathway in an early-time regime. Optimized CP/QD phase separation induces end-on chain orientation and strengthens intrachain excitonic coupling, generating a vertical driving force for intrachain-mediated S1 dissociation along the z-axis. This force interacts with a lateral driving force in the xy-plane—stemming from the conduction-band offset—that biases CP electron density toward QD domains. The interplay between the two forces introduces a kinetic bottleneck that delays exciton relaxation and polaron formation, thereby increasing the probability of radiative recombination and the photoluminescence quantum yield. Our findings provide a strategy to regulate exciton decay pathways and improve CP-based device efficiency.