A Composite Interlayer Enabling Simultaneous Performance Enhancement in Quantum Dot Solar Cells and Photodetectors ^†

Comprehensive Summary Quantum dots (QDs) have attracted significant attention in devices such as solar cells and photodetectors. Although polymer‐based hole transport layers (HTLs) have been employed in QD devices, their mechanical flexibility remains underexplored and insufficient for wearable applications. Here, we present a novel interlayer design for PbS QD solar cells and photodetectors by incorporating a low‐cost thermoplastic elastomer, SEBS (styrene‐ethylene‐butylene‐styrene), into the polymer HTL. The addition of 10 wt% SEBS promotes a more ordered molecular packing of PM6. As a result, PbS QD solar cells achieved a power conversion efficiency of 11.43%, while the corresponding photodetectors exhibited a high specific detectivity of 2.12 × 10 13 Jones—among the highest reported values. Beyond performance improvements, SEBS significantly enhances the mechanical flexibility of the HTLs. This work presents a new and effective strategy for simultaneously optimizing the optoelectronic performance and mechanical robustness of QD‐based devices.