Incorporating a nonfused electron acceptor into double-cable conjugated polymers for single-component organic solar cells with a photo response up to 900 nm

The manipulation of end groups in near-infrared (NIR) acceptors incorporated in double-cable conjugated polymers plays a pivotal role in governing the film morphology and charge transport properties in single-component organic solar cells (SCOSCs). In this study, we employ a NIR-photoresponse acceptor, comprising para-substituted benzene and 4H-cyclopenta[1,2-b:5,4-b′]dithiophene (CPDT) as the core and 2-(3-oxo-2,3-dihydroinden-1ylidene)malononitrile (IC) as the end group, into the double-cable conjugated polymers. By varying the degree of fluorination on the end group, we systematically tuned the optical and electronic characteristics of these materials. Three different double-cable polymers, namely, PF-0 (without fluorination), PF-2 (with two fluorine atoms), and PF-4 (with four fluorine atoms), are successfully applied in SCOSCs. Remarkably, the PF-4-based SCOSC exhibits an impressive power conversion efficiency of 7.60%, accompanied by a high photocurrent of 18.56 mA/cm² and broad photoresponse spanning from 300 to 900 nm. The observed enhanced performance is attributed to the increased crystallinity and improved charge transport properties in PF-4. This study sheds light on the crucial role of end-group engineering in advancing the development of efficient SCOSCs.