Asymmetric Side-Group Engineering of Nonfused Ring Electron Acceptors for High-Efficiency Thick-Film Organic Solar Cells.

A nonfused ring electron acceptor (NFREA), designated as TT-Ph-C6, has been synthesized with the aim of enhancing the power conversion efficiency (PCE) of organic solar cells (OSCs). By integrating asymmetric phenylalkylamino side groups, TT-Ph-C6 demonstrates excellent solubility and its crystal structure exhibits compact packing structures with a three-dimensional molecular stacking network. These structural attributes markedly promote exciton diffusion and charge carrier mobility, particularly advantageous for the fabrication of thick-film devices. TT-Ph-C6-based devices have attained a PCE of 18.01% at a film thickness of 100 nm, and even at a film thickness of 300 nm, the PCE remains at 14.64%, surpassing that of devices based on 2BTh-2F. These remarkable properties position TT-Ph-C6 as a highly promising NFREA material for boosting the efficiency of OSCs.