Synthesis and Photovoltaic Properties of a Polythiophene Derivative with Triphenylamine-Vinylene Conjugated Side Chain Attaching Carbonyl End Group

A new two-dimensional conjugated (2D conjugated) and side chain isolated polythiophene derivative with a dodecane carbonyl group terminated triphenylamine-vinylene (CTPA) conjugated side chain and unsubstituted terthiophene spacer, PT4-CTPA, was designed and synthesized. Compared to its polymer analogue of PT2-TPA (with only one thiophene spacer and without the pendant electron-deficient group), the 2D-conjugated and side chain isolated PT4-CTPA with the electron-withdrawing carbonyl group on the conjugated side chain shows a lower lying HOMO (the highest occupied molecular orbital) energy level at 5.24 eV and enhanced absorption of the polymer backbone. A bulk heterojunction polymer solar cell with the polymer as a donor and (6,6)-phenyl C71-butyric acid methyl ester as an acceptor demonstrated a power conversion efficiency (PCE) of 1.56% with an open circuit voltage of 0.7 V under AM1.5G, 100 mW/cm2. PCE is more than seven times higher than that of PT2-TPA (0.21%, under same experimental conditions). (c) 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E822E831, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21324