Efficient Organic Semiconductors Containing Fluorine-Substituted Benzothiadiazole for Solution-Processed Small Molecule Organic Solar Cells

초록

The synthesis and photovoltaic characteristics of new organic semiconductors, [bisDMFA-Th]-BT-HxTh(3) (1), [bisDMFA-Th]-MonoF-BT-HxTh(3) (2), and [bisDMFA-Th]-DiF-BT-HxTh(3) (3), are reported. These semiconductors have an unsymmetrical donor A-acceptor-donor B (D-A-A-D-B) framework composed of a benzothiadiazole (BT; fluorinated or unfluorinated) acceptor between two different donors bisDMFA and terthiophene. We have demonstrated that these compounds are suitable for use in p-type organic semiconductors for high efficiency solution-processed small molecule organic solar cells (SMOSCs), for which we achieved a remarkable power conversion efficiency of 4.24% with a maximum V-oc of 0.89 V. The fluorine substitution on BT decreased its HOMO level and increased hole mobilities of [bisDMFA-Th]-BT-HxTh(3) derivatives, leading to an increased V-oc in the SMOSCs and improved hole carrier transport properties of the material. In addition, we determined that the insertion of a TiOx functional layer into a bulk heterojunction (BHJ) solar cell significantly reduced the interfacial resistance between the photoactive film and metal electrode, resulting in an increased photocurrent with facile electron transfer between these two layers.

키워드