Efficient monolithic perovskite/organic tandem solar cells and their efficiency potential

A high-performance monolithic perovskite/organic tandem solar cell based on the integration of a large bandgap CsPbI2Br inorganic perovskite front cell with a narrow bandgap PM6:Y6-based or PTB7-Th:O6T-4F-based bulk-heterojunction organic rear cell is demonstrated. Large bandgap inorganic perovskites are well suited candidates for the front cell due to their excellent optoelectronic properties and broad absorption for visible light, they also possess smaller voltage loss (Eloss) and higher external quantum efficiency (EQE) response when compare to their organic counterparts with approximate bandgap. Low bandgap organic solar cells offer potentially better stability and absorption tunability compared with the Sn-based perovskite counterparts, making them be good candidates for the rear cell of the tandem cells. As a result, the best power conversion efficiency (PCE) of the perovskite/organic tandem cell presented in this work reaches over 18%. In addition, based on the photovoltaic performance parameters (EQE, fill factor (FF), Eloss) that have already been achieved in state-of-the-art organic and perovskite solar cells, we further evaluate the potential PCE of the perovskite/organic tandem cells, showing a maximum calculated PCE of over 31% when the bandgaps of the subcells are optimized. This work paves the way for the development of hybrid tandem solar cells with promising performance.