High Efficiency and Narrow Emission Band Pure-Red Perovskite Colloidal Quantum Wells

Abstract

Colloidal quantum wells (CQWs) have excellent optical performance, such as ultranarrow emission, due to strong quantum confinement in the vertical direction. However, there are few reports on metal halide perovskite CQWs with high-purity red emission (∼630 nm) for the display application, owing to the broadened photoluminescence spectrum and beyond the red emission range. Herein, we successfully synthesize high-quality CsPbI 3 CQWs in a strong electronegative solvent (mesitylene), which cut the chemical reaction rate of the precursor system to slow down the crystal nuclei growth. The number of PbI 6 4− octahedral layers (n) of CQWs can be regulated to achieve the emission of the CQW shift from orange (596 nm, n = 3) to red (626 nm, n = 4). The pure-red-emitting CQWs have a high photoluminescence quantum yield of 99% and a narrow emission bandwidth (28 nm). The Commission Internationale de l'Eclairage coordinates (0.69, 0.31) meet the requirement of the Rec. 2020 standard.

Bandgap and dimension regulation of CsPbI3 perovskite through a bromine-terminated ligand for efficient pure red electroluminescence

“…[8][9][10][11][12] However, the efficient emission in the pure red range (620-660 nm) is still a major challenge that limits the development of PeLEDs for display applications. 13,14 Compared with organicinorganic hybrid perovskites, the better chemical stability of allinorganic CsPbI 3 makes it an attractive class of material for long-term stable red PeLEDs. 15,16 In order to regulate the light emission to the pure red band, halogen doping is normally used.…”

Operational Stability Issues and Challenges in Metal Halide Perovskite Light-Emitting Diodes

“…As shown in Figure 5b, a series of ligand exchange strategies have been proposed to passivate the surface defects, 13 adjust the Fermi level 67 and exciton binding energy, or replace the original long carbon chain ligands 30 to improve spectral stability or accelerate charge mobility of nanocrystal films. Colloidal nanocrystals can also use the quantum confinement effect to change their band gap to the emission waveband of pure-red 68 or pure-blue. 51 However, in Pe-LEDs based on a reduced-dimensional perovskite film, it is difficult to achieve high-performance pure red (blue) light emission without the aid of mixed halogens.…”

Electron–Hole Binding Governs Carrier Transport in Halide Perovskite Nanocrystal Thin Films

“…The combination of quantum confinement and halide composition provides a spectral tunability from 390 nm up to 800 nm, , and quantum yields approaching unity have been reported. , For various reasons, not all spectral regimes have improved in lock-step, with especially the deep blue regions lagging behind . A workaround comes in the form of two-dimensional NPLs, which can be synthesized with a monolayer-precise control over thickness, leading to a highly tunable, efficient blue luminescence. − Additionally, NPLs exhibit extremely fast radiative decay rates, narrow emission line widths, and directional emission. − Both the fundamental material properties and the NPL interaction in an ensemble are of great importance for device operation. In NPLs, high binding energies of electron–hole pairs render excitons the dominant carrier species.…”