Tuning the performance of PSCs using rare-earth elements

Perovskite solar cells (PSCs) are emerging and promising alternatives to the market-leading solar cells due to their high performance, low fabrication cost, and versatile material modification. There are still opportunities to enhance the performance of PSCs, such as regulating mismatched absorption and limiting degradation brought about by some parts of light. Rare-earth elements (REEs) have the potential to be useful in this context. Due to their diverse energetic transition orbitals, REEs can transform ultraviolet (UV) and infrared (IR) light into visible light, which helps to improve the photostability of PSCs in addition to allowing more light absorption. Furthermore, their reversible redox potential can help prevent degradation caused by the redox reaction of other functional materials used in PSCs. As interface modifiers, REEs have the ability to induce the formation of a donor-acceptor complex, which can overcome the interface barrier and enable high charge-carrier collecting ability. In this regard, we will scrutinize PSCs that utilize REEs as electron transporting materials, hole transporting materials, additives in perovskites, and interface modifiers. We also offer the possible future research directions and limitations of using REEs in PSCs for high stability and increased efficiency.