Thermally Stable Red-Emitting Mixed Halide Perovskite Nanocrystals Enabled by Solid Reaction and Co-Doping Process

摘要

Rapid performance degradation as temperature increases for metal halideperovskite nanocrystals (NCs) greatly restricts the practical application forlighting and display. This problem is even more grievous for the mixed-halideperovskite NCs because of severe ions migration. Here, a solid-reactionprocess in the N_2 atmosphere is devised, in which the red-emitting (631 nmwavelength) mixed halide CsPbBr_(1.5)I_(1.5) NCs with a coating of SiO_2 shell areachieved. Meanwhile, the Zn~(2+) and K~+ ions are co-doped into the crystal latticeto enhance the radiative decay rate and decrease the trap density of theNCs. The photoluminescence quantum yield of the co-doped NCs reaches64.5%, which is one of the highest values for the reported mixed-halideperovskite NCs obtained by the solid reaction. Importantly, the dopant of K~+enters into the interstitial position of the perovskite structure to increase thestructural rigidity, which inhibits exciton–phonon interaction and elevatesthermal activation energy, thus improving thermal quenching resistance tosustain high emission intensity at high temperature (>353 K). Furthermore,the red backlight emitting diode based on the NCs exhibits no decay in luminescenceintensity after continuous operation for 700 h at 353 K, representingremarkable stability for the commercial application.