Main‐chain alternating fullerene and dye oligomers for organic photovoltaics

• DOI: 10.1002/pi.5273
• Publication Date: 2016-09-28T13:19:49Z
• Authors: Meera Stephen; Simon Dowland; Alberto Gregori; Hasina H Ramanitra; Hugo Santos Silva; Craig MS Combe; Didier Bégué; Christine Dagron‐...; Graham E Morse; Kristijonas Genev...; Kestutis Arlauskas; Gytis Juška; Andreas Distler; Roger C Hiorns
• Keywords: HOMO/LUMO; Moiety; Thermal Stability; Side chain

Abstract This work demonstrates for the first time that it is possible to prepare alternating oligomers, containing both dyes and fullerenes in repeating structures, act as electron acceptors bulk heterojunction devices. A sterically controlled azomethine ylide cycloaddition polymerization employed with either C 60 or phenyl‐C 61 ‐butyric acid methyl ester (PCBM) dye diketopyrrolopyrrole (DPP). The former results low molecular weights of around 5600 g mol −1 , whereas latter, PCBM, enables formation more soluble chains higher ca 11 200 . Remarkably, cyclic voltammetry shows incorporation PCBM into main‐chain raises lowest unoccupied orbital by 380 meV due in‐chain bis‐additions. observation complete quenching DPP fluorescence fullerene moiety, combined computer modelling studies, indicates energy transfers between intra‐chain moieties. Proof‐of‐concept devices show efficiencies most likely as‐yet‐unoptimized preparation but hint at possibilities these novel bi‐functionalized, their high V oc 0.89 an example low‐bandgap polymer, KP115, reasonable charge mobilities 1 × 10 −4 cm 2 s making this new class materials strong interest applications. Furthermore, good thermal stability above 300 °C stabilization photovoltaic against degradation confirm pathway a wide range dye/fullerene structures extremely promising. © 2016 Society Chemical Industry