Zirconium Phosphate‐Directed Matrix‐Assisted Re‐Precipitation (MARP) of Perovskites for Phase Engineering and Stability

Abstract A novel “matrix assisted reprecipitation” (MARP) strategy is introduced employing exfoliated zirconium phosphate (Exf‐ZrP) inorganic matrix to direct perovskite (Cs 4 PbBr 6 ‐CsPbBr 3 ) crystallization and enable post‐synthetic phase engineering. A sub‐1 wt.% loading of the Exf‐ZrP matrix not only boosts the photoluminescence quantum yield (PLQY) of the perovskite to 75%, a 2.4‐fold enhancement over the matrix‐free, conventional, ligand‐assisted reprecipitation (LARP) method‐but also promotes the formation of larger CsPbBr 3 domains (up to 45 nm) within the Cs 4 PbBr 6 host, resulting in a red shifted emission at 520 nm and significantly improves perovskite dispersibility. The Exf‐ZrP matrix also directs a water‐induced solid‐state phase conversion of Cs 4 PbBr 6 into CsPbBr 3 , resulting in enhanced photoluminescence (PL) with additional red shift upto 530 nm, characteristic of high‐purity green wavelength suitable for display technologies. Moreover, MARP perovskites exhibit enhanced thermal and photostability compared to LARP perovskites. The results demonstrate a new paradigm for nanoengineered perovskite systems with on‐demand optical properties and stability, expanding their functional scope in emerging material platforms.