Organic solar cells based on acceptor-functionalized diketopyrrolopyrrole derivatives

Abstract

The synthesis and characterization of three solution processable diketopyrrolopyrrole (DPP) derivatives featuring acceptor units attached to the core by alkyne linker units is reported. Cyclic voltammetry and DFT calculations indicate that the DPP derivatives possess similar HOMO and LUMO energies. Solar cells were fabricated by blending the synthesised DPP derivatives with PC71BM. The influence of donor:acceptor blend ratio, film thickness, annealing temperature and annealing time on device performance was studied. Differences in device performance were related to atomic force microscopy measurements of the films. The highest power conversion efficiency of 1.76% was achieved for the DPP derivative functionalized with an aldehyde electron withdrawing group with 1:0.7 donor:acceptor ratio when active layer was annealed for 10 minutes at 110 oC.