Diketopyrrolopyrrole: Adjustment of Molecular Properties

摘要

Four derivatives of diketopyrrolopyrrole (DPP) end-capped with benzofuran, benzooxazol, benzothiofen or benzothiazol were used as electron donating material in bulk heterojunction organic solar cells (BHJ OSC). The derivatives were designed to provide increased open circuit voltage due to lower HOMO and thus to approach ideal molecular energy leveling. All of the new materials (benzooxazol, benzothiofen benzothiazol DPPs) showed limited recrystallization upon gentle annealing temperatures compatible with flexible devices fabrication. As a result of lower charge carrier mobility of benzooxazol and benzothiazol derivatives the resulting power conversion efficiency (PCE) was poor. The benzothiofen derivative exhibited improved PCE in as-cast devices compared to previously reported benzofuran DPP. However, due to limited recrystallization, the overall PCE was also not improved in the annealed devices.