A Comprehensive Review on Mechanisms and Applications of Rare-Earth Based Perovskite Nanocrystals

Rare earth (RE) ions, with abundant 4f energy level and unique electronic arrangement, are considered as substitutes for Pb(2+)in per-ovskite nanocrystals (PNCs), allowing for partial or complete replacement of lead and minimizing environmental impact. This review provides a comprehensive overview of the characteristics of RE-doped PNCs, including up-conversion luminescence, down-conversion luminescence, and quantum confinement effects, etc. Additionally, RE doping has been found to effectively suppress defect formation, reduce nonradiative recombination, enhance photoluminescence quantum yield (PLQY), and even allow for controlling over the mor-phology of the nanocrystals. The review also highlights the recent advancements in lead-free RE-based perovskites, especially in the case of Eu-based perovskites (CsEuBr(3 )and CsEuCl3). Furthermore, it briefly introduces the applications of PNCs in various fields, such as perovskite solar cells (PSCs), luminescent solar concentrators (LSCs), photodetectors (PDs), and light-emitting diodes (LEDs). A sys-tematic discussion on the luminescence mechanisms of RE-doped PNCs and lead-free RE-based perovskites is provided, along with an outlook on future research directions. The ultimate goal of this review is to provide guidance for the development of RE-based perov-skite optoelectronic devices.