Thiophene-free diphenyl-amino-stilbene-diketo-pyrrolo-pyrrole derivatives as donors for organic bulk heterojunction solar cells

Abstract

AbstractAn extended study on a group of four soluble diphenyl-amino-stilbene based diphenyl-diketopyrrolo-pyrrole molecules has been carried out. Using the materials in thin-film transistors it was shown that the above-mentioned compounds can be successfully used as donors in organic photovoltaic devices. Influence of the molecular symmetry and solubilizing chain on the morphology and solar cell performance are described. It was shown that a shorter and non-branched ethyl acetate chain leads to higher charge carrier mobility, short circuit current, and better fill factor. After the basic optimization, a power conversion efficiency of about 1.5 % was reached. This, to the best of our knowledge, is the highest reported efficiency of thiophene-free small-molecule diketo-pyrrolopyrroles.