Fully Fused Indacenodithiophene‐Centered Small‐Molecule n‐Type Semiconductors for High‐Performance Organic Electronics

Abstract

Developing novel n‐type organic semiconductors is an enduring research endeavour, given their pivotal roles in organic electronics and their relative scarcity compared to p‐type counterparts. In this study, a new strategy was employed to synthesize n‐type organic semiconductors featuring fully‐fused conjugated backbone. By attaching two sets of adjacent amino and formyl groups to the indacenodithiophene‐based central cores and triggering a tandem reaction of Knoevenagel condensation‐intramolecular cyclization, DFA1 and DFA2 were realized. The solution‐processed organic field effect transistors based on DFA1 exhibited unipolar n‐type transport character with a decent electron mobility of ca. 0.10 cm2 V‐1 s‐1 (ca. 0.038 cm2 V‐1 s‐1 for DFA2 based devices). When employing DFA1 as a third component in organic solar cells, a high power conversion efficiency of 19.2% can be achieved in ternary devices fabricated with PM6:L8‐BO:DFA1. This work paves a new pathway in the molecular engineering of n‐type organic semiconductors, propelling relevant research forward.