Cu doping-enhanced emission efficiency of Mn2+ in cesium lead halide perovskite nanocrystals for efficient white light-emitting diodes

Enhancing emission efficiency of Mn2+ in blue-orange dual-emitting Mn doped cesium lead halide perovskite nanocrystals (NCs) with high photoluminescence quantum yields (PL QYs) is important to fabricate high efficiency white light emitting diodes for solid state lighting. The synthesis and luminescent properties of Mn doped CsPbCl3-xBrx NCs through anion exchange of Mn and Cu co-doped CsPbCl3 NCs with PbBr2 at room temperature were studied by means of steady-state and time-resolved PL spectroscopy. The high Mn2+ PL QYs of 52-63% were obtained in the initial Mn and Cu co-doped CsPbCl3 NCs synthesized under various Mn/Pb/Cu molar ratios at 190 degrees C by hot injection method. A record Mn2+ PL QY up to 53% was achieved in the blue (450 nm) -orange (600 nm) dual-emitting Mn and Cu co-doped CsPbCl3-xBrx NCs through anion exchange. The enhancement of Mn emission efficiencies was attributed to reduced defect states in the doped NCs due to the incorporation of Cu ions. The efficient warm white light emitting diodes with color rendering index of 85 and luminous efficacy of 69 lm/W were fabricated by combination of the blue-orange dual-emitting Mn and Cu co-doped CsPbCl3-xBrx NCs and green emissive CsPbBr3@Cs4PbBr6 core/shell NCs. The improved color rendering index was demonstrated with increasing Mn content.