Synthesis and photovoltaic properties of a solution-processable organic molecule containing dithienylbenzotriazole and triphenylamine

A new solution-processable organic small molecule, namely, TPA–DTBTz–TPA with triphenylamine (TPA) as electron donor and dithienylbenzotriazole (DTBTz) as electron acceptor was synthesized by a Heck cross-coupling reaction, and characterized by 1H NMR, TGA, UV–vis absorption, and cyclic voltammetry. The compound was found to be easily soluble in common organic solvents, such as chloroform, tetrahydrofuran and chlorobenzene with excellent film forming properties. TPA–DTBTz–TPA film exhibits an absorption band from 300 to 620 nm. The organic solar cells based on a blend of TPA–DTBTz–TPA and PC60BM (1:2, w/w) show a power conversion efficiency (PCE) of 0.93% with a short circuit current density of 4.43 mA/cm2 and an open circuit voltage of 0.74 V, under the illumination of AM 1.5, 100 mW/cm2.