Recent progress on efficient perovskite/organic tandem solar cells

The concept of tandem solar cells (TSCs) is an effective way to substantially further improve the efficiency of solar cells. The excellent optoelectronic properties and bandgap tunability of perovskites make them promising for constructing efficient TSCs. Currently, TSCs based on perovskite have been extensively studied. Besides, the performance of organic solar cells has been greatly improved recently due to the wider and more efficient spectral utilization. Accordingly, research on perovskite/organic TSCs has garnered significant attention. It has potential application advantages in emerging fields such as wearable devices by virtue of flexibility. In addition, orthogonal solvents can be adopted to realize the separate preparation of subcells with the solution method, which greatly reduces fabrication complexity; moreover, fabrication with less equipment significantly cuts down the device cost. Meanwhile, organics with more adjustability on the optoelectronic properties provide more tuning strategies for high-performance perovskite/organic TSCs. However, comprehensive and timely reviews on the perovskite/organic TSCs are deficient. Therefore, we expect to accomplish a review on this innovative TSCs to facilitate researchers with a deeper understanding of perovskite/organic TSCs. Herein, we firstly review the significant progress of perovskite and organic solar cells. Then, current achievements of perovskite/organic TSCs are summarized and introduced with a particular focus on the device structure design. Finally, we discuss existential challenges and propose effective strategies for future engineering.