Stability of Wide-Bandgap Perovskites for Tandem Applications: A Review
Fengtao Pei, Qi Chen, Yan Jiang
Abstract
The bandgap tunability of organic–inorganic hybrid perovskite materials makes them ideal light absorbers in tandem configuration, enabling breakthroughs beyond the theoretical efficiency limit of single-junction solar cells. Representatively, the monolithic perovskite/silicon tandem solar cell has achieved an astounding recorded efficiency of 34.6%. As the top cell absorbers in tandem solar cells, wide-bandgap (WBG) perovskites obtained by on-demand regulation of the iodide–bromine (I–Br) ratio, are responsible for capturing high-energy photons to reduce thermalization losses. However, typical I–Br WBG perovskites suffer severe intrinsic instability, primarily due to halide segregation when exposed to light and/or heat. The instability compromises both the efficiency and durability of tandem devices, posing a major barrier to technology commercialization. In this short review, we first provide a classified overview of recent efforts aimed at inhibiting halogen segregation in WBG perovskites, with a particular focus on the often-overlooked issue of cationic segregation. Furthermore, we highlight that stability could be enhanced by strengthening the interactions between anionic and cationic components and/or employing new constituents in the material formula beyond the I/Br system. Finally, we discuss the primary challenges and offer perspectives on advancing stable WBG perovskites for efficient and stable tandems.