Effect of molecular spatial configuration on the photovoltaic properties of triphenylamine-containing D–A structured organic molecules

Abstract

The photovoltaic properties of four triphenylamine (TPA)-containing organic molecules were studied by fabricating bulk-heterojunction organic solar cells (OSCs) with the organic molecules as the donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) as the acceptor. The molecules possess a D–A structure with TPA as the donor unit and benzothiadiazole (BT) as the acceptor unit, and have different spatial configurations with TPA as the core and with single-armed configuration (linear molecule TPA-BT), two-armed configuration (bi-armed molecule b-TPA-BT) and three-armed configuration (tri-armed molecules t-TPA-BT and S(TPA-BT)). The OSCs based on TPA-BT, b-TPA-BT, t-TPA-BT and S(TPA-BT) display power conversion efficiencies of 1.33%, 2.33%, 3.14% and 3.37%, respectively, under the illumination of AM 1.5G, 100 mW cm−2. The results indicate that the spatial configuration of the molecules influenced the photovoltaic properties significantly and the star-shaped molecules are superior to the linear and two-armed molecules in the application as donor materials in solution-processed OSCs.