Stereoisomerism of ladder-type acceptor molecules and its effect on photovoltaic properties

Asymmetrical side chains were widely used in conjugated molecules, but related stereoisomeric phenomenan is rarely investigated. Herein, two stereoisomers based on ladder-type acceptor IDT-BT-R with asymmetrical side chains were synthesized and their properties were studied. Compared to cis -IDT-BT-R, trans -IDT-BT-R with centrosymmetrical structure showed stronger crystallinity and more ordered molecular packing. As a result, trans -IDT-BT-R based photovoltaic devices exhibited higher charge transport properties and superior power conversion efficiency (PCE) up to 9.43%.