Precisely Manipulating Molecular Packing via Tuning Alkyl Side-Chain Topology Enabling High-Performance Nonfused-Ring Electron Acceptors

In the development of high-performance organic solar cells (OSCs), the self-organization of organic semiconductors plays a crucial role. This study focuses on the precisely manipulation of molecular assemble via tuning alkyl side-chain topology in a series of low-cost nonfused-ring electron acceptors (NFREAs). Among the three NFREAs investigated, DPA-4, which possesses an asymmetric alkyl side-chain length, exhibits a tight packing in the crystal and high crystallinity in the film, contributing to improved electron mobility and favorable film morphology for DPA-4. As a result, the OSC device based on DPA-4 achieves an excellent power conversion efficiency of 16.67 %, ranking among the highest efficiencies for NFREA-based OSCs. Herein, we report a series of low-cost nonfused-ring electron acceptors (NFREAs) with precisely regulated alkyl side-chains. It is found that tuning the topology of alkyl side-chains can effectively manipulate molecular assemble. Hence, the NFREA DPA-4 with asymmetric alkyl side-chains exhibits a tight packing and high crystallinity, thus contributing to improved electron mobility and boosted power conversion efficiency (16.67 %).+image