Confined Synthesis of CsMnBr ₃ :Pb ²⁺ Nanocrystals in Mesoporous Metal–Organic Frameworks: Defect Modification, Optical Modulation, and Optoelectronic Applications

Abstract Metal halide perovskite nanocrystals (NCs) have been considered as promising candidates for optoelectronic applications due to its outstanding photophysical property. And yet, the poor stability and toxicity problems severely hinder its practical application. Herein, a “ship in bottle” strategy is proposed for the in situ growth of low‐toxicity CsMnBr ₃ :Pb ²⁺ NCs in the mesopores of macro‐microporous UiO‐66 (M‐UiO‐66) nanosphere. The resulting CsMnBr ₃ :Pb ²⁺ @M‐UiO‐66 (CMB@UiO) nanoparticles emit strong red light at 648 nm with a wide full width at half‐maximum of 96 nm, a high photoluminescence quantum yield of 76.2%, and significantly improved stability. The ultralow temperature‐dependent spectral measurements demonstrate the high optical phonon energy (54 meV) of CMB@UiO nanoparticles. The femtosecond transient absorption analysis clearly demonstrates the suppression of nonradiative recombination process of CsMnBr ₃ :Pb ²⁺ NCs by M‐UiO‐66 encapsulation. And the finite difference time‐domain simulations reveal that the ordered mesopore structure of M‐UiO‐66 have strong waveguide effect on the emission of embedded CsMnBr ₃ :Pb ²⁺ NCs, which effectively inhibits the reabsorption loss and increases the luminescent efficiency. Furthermore, the CMB@UiO nanoparticles demonstrate promising application in white light‐emitting diodes, which possess high luminous efficiency (69.4 lm W ⁻¹ ) and excellent operation stability. This work paves the way for the optoelectronic application of low‐toxicity perovskite NCs.