A versatile small molecular electron donor with 2-dimensional conjugation structure for efficient organic solar cells compatible with both fullerene and non-fullerene electron acceptors. (February 2019) - Jung, Jae Woong
Abstract: We herein report design, synthesis and photovoltaic properties of a small molecular donor composed of bithienyl-substituted benzo [1, 2-b:4, 5-b′]dithiophene flanked with diketopyrrolopyrrole. For constructing the 2-dimensional conjugated architecture, it is functionalized with bithienyl side chains onto the benzo [1, 2-b:4, 5-b′]dithiophene, resulting in intense absorption in UV–Vis region, a low optical band gap, low-lying energy levels and high crystallinity of the resulting donor molecule. These affirmative properties for photovoltaic applications affords the power conversion efficiency of 5.35% with a fullerene acceptor, while even higher efficiency of 5.95% was achieved using a non-fullerene acceptor. This work suggests a design strategy of 2-dimensional conjugation of small molecular donor for efficient organic solar cells compatible with multiple electron acceptors. Highlights: A 2-D conjugated small molecular electron donor, BTBDT (DPP)2, was designed and synthesized. BTBDT (DPP)2 exhibited low band gap (1.63 eV), low-lying energy levels and high crystallinity. Organic solar cells of BTBDT (DPP)2 exhibited 5.35% with PC71 BM and 5.95% with ITIC as electron acceptor, respectively.