Homo-tandem structures to achieve the ideal external quantum efficiency in small molecular organic solar cells

Abstract

In this study, we report a homo-tandem structure of small molecular organic solar cells (SMOSCs) using identical single-junction devices as sub-cells. The trade-off between the absorption and internal quantum efficiency (IQE) of single-junction devices tends to limit the external quantum efficiency (EQE). However, multiple-stacked thin cells with maximized IQE in homo-tandem structures amplify the absorption to achieve the ideal EQE. As a result, a high power conversion efficiency of 7.81% is achieved in tetraphenyldibenzoperiflanthene (DBP): C-70-based homo-tandem SMOSCs, which is 21.8% higher than that in a single-junction device. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement