Stable and Efficient Perovskite‐Based Luminescent Solar Concentrators Enabled by Mn 2+ Doping and Polymer Modification of Perovskite Nanocrystals

Abstract Iodine‐based perovskite nanocrystals (NCs) have emerged as a promising fluorescent material for luminescent solar concentrators (LSCs) due to their high photoluminescence quantum yield (PLQY), facile synthesis, and broad absorption spectrum. However, conventional formamidinium (FA, CH(NH 2 ) 2+ ) perovskite suffers from phase‐transition instability under ambient conditions, limiting their practical applications. In this study, Mn 2+ ‐doped FAPbI 3 NCs, synthesized via a perovskite transformation method, are presented, which serve as highly efficient luminescent emitters for LSCs. The combination of Mn 2+ doping and a perovskite transformation method not only increased the PLQY from 60 to 91% but also significantly improved the air and light stability of the NCs. Moreover, novel metal‐coordinating polymers are fabricated via the nucleophilic addition reaction of poly(isobutylene‐alt‐maleic anhydride) (PIMA) copolymer and (3‐aminopropyl) triethoxysilane (APTES), forming a protective matrix that enhances the stability and PLQY of the NCs. By incorporating these Mn 2+ ‐doped FAPbI 3 NCs into the LSC device (geometric factor of 12.5), an optical conversion efficiency of 3.7% is achieved. Notably, the device demonstrated acceptable stability, with its optical efficiency decreasing from 3.7 to 3.3% after 8 h of continuous exposure to simulated sunlight, retaining 89.2% of its initial performance. Furthermore, the LSC exhibited reasonable long‐term durability, highlighting its potential for practical applications.