Efficient and Color-Tunable Quasi-2D CsPbBr_xCl_3–x Perovskite Blue Light-Emitting Diodes

Abstract

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 CsPbBr x Cl 3−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 CsPbBr x Cl 3−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 NiO x /LiF hole transport layer with high affinity to precursor solution for improving the film quality of quasi-2D CsPbBr x Cl 3-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 CsPbBr x Cl 3-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.

Ultrafast Thermodynamic Control for Stable and Efficient Mixed Halide Perovskite Nanocrystals

“…So, most of the blue LEDs based on dimension engineering have emission wavelengths at 480 nm or larger, close to sky blue, including the recently reported highest and second most efficient blue LEDs. [ 21,22,28–31 ] Moreover, such range could not meet the standard of National Television System Committee, which indicates that the emission of blue LED must be located at around 470 nm or bluer. [ 9 ] In addition, controlling the formation of single quantum wells or achieving effective charge transfer between different quantum wells is challenging, which usually results in multiple emission peaks.…”

Controlling Spatial Crystallization Uniformity and Phase Orientation of Quasi‐2D Perovskite‐Based Light‐Emitting Diodes Using Lewis Bases

“…This tunability comes about because of the wide selection of corresponding chemical precursors and the potential for quantum confinement via controlled dimensionality . Subsequent to the intensive efforts made to achieve high‐performance devices with 3D‐structured perovskites via engineering of interfacial and bulk properties for a better quality of films, quasi‐2D perovskites have been considered as promising contenders for the development of solution‐processed devices . Quasi‐2D perovskites can be formed by introducing large aliphatic or aromatic alkylammonium cations, such as phenethylammonium (PEA + ), butylammonium (BA + ), and octylammonium (OA + ), that can slice the 3D perovskite frameworks into 2D layers .…”

Fabrication of Hybrid Nanostructures via Nanoscale Laser‐Induced Reshaping for Advanced Light Manipulation

“…Recently, the combination of these two paradigms in the form of metal–dielectric (hybrid) nanostructures (nanoantennas and metasurfaces) has allowed the advantages of both plasmonics and all‐dielectric nanophotonics to be utilized . The hybrid nanostructures are prospective for beam steering, optical switching, generation of high harmonics, directional emission, engineering of the local density of states, magneto‐optical activity, ultrahigh optical absorption, room‐temperature laser emission, and enhancement of photophysical effects …”