Diketopyrrolopyrrole-based conjugated small molecules bearing two different acceptor moieties for organic solar cells

Abstract

Three A(1)-D-A(2)-D-A(1)-type conjugated molecules (A: acceptor, D: donor), containing diketopyrrolopyrrole (DPP) acceptors, another weaker acceptor, and thiophenes as common donors, were synthesized. The molecules exhibited strong absorption from 500 nm to the near-IR wavelength region, and different molecular energy levels. The three molecules synthesized were applied in solar cells made with phenyl C-71-butyric acid methyl ester, and thienopyrroledione (TPD) (DPP)(2) exhibited the highest power conversion efficiency of 3.37% owing to its appropriate internal morphology and relatively high open circuit voltage, which is conferred by its relatively low-lying highest occupied molecular orbital level. (C) 2016 Elsevier B.V. All rights reserved.