Efficient and Color-Tunable Quasi-2D CsPbBrxCl3-x Perovskite Blue Light-Emitting Diodes

Metal halide perovskites are emerging as promising candidate materials for light-emitting diodes (LEDs) due to their high luminescence, color purity, tunable bandgaps, and solution processabilities. In the past several years, the metal halide perovskite based LEDs (PeLEDs) in the green and red light spectral range have been demonstrated in high brightness and good efficiency. However, the performance of blue PeLED is still limited by the low blue light emission efficiency of present metal halide perovskite materials. Here, we report a facile solution method to fabricate a series of quasi-2D CsPbBrxCl3-x perovskite films with high photoluminescent quantum yields (PLQYs) in the blue light spectral range. By compositional engineering via increasing the content of chloride, we achieved the tunable light emission wavelength of quasi-2D CsPbBrxCl3-x perovskite films from green (504 nm) to blue (470 nm) with a high PLQY up to 42% at 486 nm. In addition, we developed a novel NiOx/LiF hole transport layer with high affinity to precursor solution for improving the film quality of quasi-2D CsPbBrxCl3-x perovskite while reducing the quenching effect of hole transport layer to as-formed perovskite film. As a result, the blue PeLEDs based on quasi 2D CsPbBrxCl3-x perovskite films show color-tunable emissions and the external quantum efficiency of 0.52% as well as high brightness of 1446 cd m(-2) are achieved at 490 nm.