Synthesis and Photovoltaic Properties of Small Molecules Based on Triphenylamine and Diketopyrrolopyrrole for Organic Photovoltaic Cells

Abstract

Various types of small molecules for donor materials of organic photovoltaics have recently been developed due to their advantages over conjugated polymers such as stronger absorption coefficient, better thermal stability and easier synthesis. In this study, we synthesized three small molecules based on triphenylamine (TPA) and diketopyrrolopyrrole (DPP), TPA(DPP)1, TPA(DPP)2, and TPA(DPP)3, in which TPA and DPP are electron-rich unit and electron-deficient unit, respectively, DPP units are attacted to the para-positions of phenyl groups in TPA to produce TPA(DPP)1, TPA(DPP)2, and TPA(DPP)3. Chemical structures and electrochemical properties of the three small molecules are measured by NMR, GC-mass, UV-vis absorption, and cyclic voltammetry. The solar cell performances of the cells with three different small molecules are measured and analyzed in terms of molecular symmetry.