Impact of self-assembly on the photovoltaic properties of a small molecule oligothiophene donor

© 2019 International Solar Energy Society The positive impact of self-assembly on the photovoltaic properties of a donor-π-acceptor oligothiophene molecule coded as CP3, which contains a barbituric acid as a terminal acceptor unit and triphenylamine as donor, enabling hydrogen-bonded spherulites to assemble in its films is described. The hydrogen-bonded supramolecular array of barbiturated-oligothiophene molecules were directly visualized by scanning electron microscopy. Bulk-heterojunction solar cells comprising CP3 and the fullerene PC61BM show a power conversion efficiency of 6.31%, which is markedly higher than a structural analogue CP4, which comprises a N-ethylrhodanine terminal acceptor unit incapable of participating in the same degree of self-assembly, supporting the impact of self-assembly in BHJ devices.