Solution-assisted layer peeling for stable and high-efficiency Zn:MAPbBr_xCl_3-x@PbBr(OH) cyan phosphors

Perovskite materials have attracted substantial attention for their promising applications in high-performance light-emitting devices. However, the development of cyan-emissive metal halide perovskites lags markedly behind their red and green counterparts among the multi-color emissive type perovskites, primarily because of their poor stability and low luminescence efficiency. Herein, PbBr(OH)-encapsulated and Zn-doped MAPbBr_xCl_3-x (MA = CH₃NH₃⁺) cyan phosphors were fabricated by in situ solution peeling from Zn-alloyed MAPbBr_xCl_3-x single crystals. Notably, the PbBr(OH) shell-encapsulated perovskite phosphors not only demonstrate excellent stability under light, heat, and exposure to organic solvents but also confine the photogenerated excitons, passivate surface defects, prevent ion migration and suppress non-radiative losses in the MAPbBr_xCl_3-x nanocrystals upon Zn doping, resulting in a high photoluminescence quantum yield (PLQY). As a representative candidate, the Zn:MAPbBr_2.2Cl_0.8@PbBr(OH) phosphor exhibits a bright cyan emission at 481 nm with a high PLQY of over 90%. The Zn:MAPbBr_2.2Cl_0.8@PbBr(OH) phosphor-based cyan light-emitting diode maintains a brightness exceeding 1000 cd m^-2 even after 24 h of continuous operation under a current of 9.8 mA with exceptional stability. Furthermore, these cyan-emissive phosphors can be utilized for overcoming the issues of "blue overshoot" and "cyan gap" in white light-emitting diodes.