Spectra tunable non-fused ring electron acceptors via incorporation of an electron-deficient unit and side-chain engineering†

Non-fused-ring acceptors are currently gaining significant attention in research due to their remarkable potential for practical application. In this study, we employed a combination of an electron-deficient unit (EDU) and side-chain engineering to synthesize a series of A–D–A′–D–A acceptors (BT-4T-1, BT-4T-2, and BT-4T-3) for high-performance organic solar cells. By utilizing the EDU, benzothiadiazole (BT), we constructed a central three-membered planar moiety via S⋯O non-covalent locking. Through systematic side-chain engineering, we could effectively regulate the absorption spectra ranging from 400 to ∼1000 nm, which is largely ascribed to the molecular configuration changes. The photovoltaic study suggested that JD-40:BT-4T-3 exhibited a well-mixed morphology conducive to efficient exciton diffusion and charge transfer, achieving a power conversion efficiency (PCE) of 11.70%.