Selective Hole and Electron Transport in Efficient Quaternary Blend Organic Solar Cells

Abstract

© 2020 Elsevier Inc. One important strategy to further enhance the efficiency of organic solar cells (OSCs) is to incorporate three or even four complementary organic materials in one cell. Such OSCs (often referred to as ternary or quaternary OSCs) can offer much broader absorption, thus better performance because one single organic material typically has a narrow absorption band. Despite the benefits, material selection and morphology control are extremely challenging for ternary OSCs already, while quaternary OSCs are not even considered feasible practically. In this manuscript, we have successfully developed a new type of quaternary blend system, which exhibits a unique “rivers and streams”-type hierarchical morphology that allows it to operate exceptionally efficiently, reaching a high PCE of 17.73%, significantly outperforming the corresponding binary and ternary devices. This type of “rivers and streams” morphology can offer unprecedented opportunities for organic solar cells with better efficiency.