P–π Conjugated Polymers Based on Stable Triarylborane with n‐Type Behavior in Optoelectronic Devices

Abstract

Abstractp–π conjugation with embedded heteroatoms offers unique opportunities to tune the electronic structure of conjugated polymers. An approach is presented to form highly electron‐deficient p–π conjugated polymers based on triarylboranes, demonstrate their n‐type behavior, and explore device applications. By combining alternating [2,4,6‐tris(trifluoromethyl)phenyl]di(thien‐2‐yl)borane (FBDT) and electron‐deficient isoindigo (IID)/pyridine‐flanked diketopyrrolopyrrole (DPPPy) units, we achieve low‐lying lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels, high electron mobilities, and broad absorptions in the visible region. All‐polymer solar cells with these polymers as electron acceptors exhibit encouraging photovoltaic performance with power conversion efficiencies of up to 2.83 %. These results unambiguously prove the n‐type behavior and demonstrate the photovoltaic applications of p–π conjugated polymers based on triarylborane.