Local Structure‐Induced Selective Interactions Enables High‐Performance and Burn‐in‐Free Organic Photovoltaics

Oligomeric acceptors (OAs) have attracted considerable attention in the organic photovoltaics (OPV) field owing to their capacity in balancing the merits from both monomeric and polymeric acceptors. A delicate control over the distortion between blocks of OAs usually determines the performance and stability of relevant OPV devices. However, it imposes great complexity to realize a controllable degree of distortion by tuning the skeleton of blocks and the position of linker between blocks. Herein, we developed a facile strategy to rationally control the geometry distortion of OAs via a straightforward substitution of alkoxy side‐chains on their blocks. This helps elucidate the integrated influences of molecular distortion and non‐bonded contacts on the selective interactions between OA molecules and between OA and host acceptor in ternary blend. We demonstrate the alkoxy‐OA molecules having stronger self‐interactions would mitigate their interactions with host acceptor, therefore alleviating the kinetic diffusion and excessive aggregation of total acceptors. Combining with a composite‐interlayer strategy by introducing a phenyl‐substituted self‐assembled monolayer to enhance the doping with polyoxometalate, an impressive efficiency of 20.1% is achieved accompanied by a negligible burn‐in loss against physical aging. This study demonstrates the validation of tuning of selective interactions towards high‐performance and burn‐in‐free OPV.