Research progress of perovskite-based triple-junction tandem solar cells

The energy conversion efficiency of single-junction solar cells is limited by the Shockley-Queisser theory and the most effective strategy to break through this limit is to fabricate multi-junction tandem solar cells. Perovskite materials provide a continuously tunable energy band structure, offering a new option for light-absorbing materials in multi-junction tandem cells. In the field of perovskite-based multi-junction tandem solar cells, triple-junction tandem solar cells have demonstrated great potential. The present paper introduces the configuration of triple-junction solar cells and its facing three scientific challenges. 1) Ensuring energy level alignment among sub-cells is a critical concern for three-junction batteries. Specifically, the top wide-band gap sub-cell must possess a band gap ranging from 1.8 to 2.2 eV; however, current perovskite material systems with wide-band gaps exhibit certain defects. 2) It is essential to achieve current matching in multi-junction tandem solar cells while optimizing the absorption layer and minimizing parasitic absorption in order to maximize the current output of solar cells. 3) The functional layers of multi-junction tandem solar cells are stacked sequentially using different deposition methods, which imposes higher compatibility requirements on the intermediate interconnect layers. Subsequently, the research progress of perovskite-based triple-junction tandem solar cells is introduced, including perovskite/perovskite/silicon tandem solar cells, perovskite/perovskite/organic tandem solar cells, and all-perovskite tandem solar cells. Their respective highest efficiencies are 19.4%, 23.87%, and 27.1%. Finally, this paper explores the research directions for further improving the performance of triple-junction solar cells. In addition to improving energy conversion efficiency, perovskite-based solar cells must also solve the stability problems in order to achieve future commercialization, and provide guidance for the development of efficient triple-junction cells.