The first preparation of electrically excited WLED based on lead-free double perovskite quantum dots

2022-07-29 0 By

Perovskite photoelectronic devices have attracted much attention because of their excellent device performance and convenient solution treatment.However, the toxicity and inherent instability of lead – based perovskites limit their commercial development.In addition, providing effective white emission from a single perovskite layer is a challenge.Researchers from Peking University have for the first time fabricated a novel electrically excited white light emitting diode based on lead-free double perovskite CS2agin 0.9Bi0.1Cl6 quantum dots (QDs).The absorption and recombination mechanism of Bi doping breaking odd-even forbidden transition in direct band gap is calculated using density functional theory.The optical and electronic characterization of the cs2Agin 0.9Bi0.1Cl6 QDS showed that the broadband emission of cs2Agin 0.9Bi0.1Cl6 QDS was caused by self-trapping excitons, and the luminescence properties remained unchanged after deposition.Qd-wled showed excellent color coordinates and relatively high color rendering index (0.32,0.32), 6432 K and 94.5, respectively.The maximum brightness is 158 CD m−2.Therefore, lead-free perovskite Cs 2 AgIn 0.9Bi 0.1Cl 6 quantum dots are promising candidates for WLED applications in the future.The paper entitled “Lead-free Double Perovskite CS2Agin0.9Bi0.1Cl6 Quantum Dots for White Light-emitting Diodes” is listed in AdvancedIn the journal Science.More exciting tik Yin search ‘materials science network’.Paper links: https://onlinelibrary.wiley.com/doi/10.1002/advs.202102895 white light-emitting diodes (WLED) on the display and the application of the lighting industry has been widely studied.An electrically excited device based on a red-green-blue cell and a photoexcited device formed by a blue emitter with a downshifting phosphorescent are two components of most Wleds.Due to their unique photoelectric properties, halide self-luminescent materials show great potential in display, illumination and energy conversion.Significant progress has been made in the field since the use of perovskite as a phosphor converting WLED was first reported in 2015.Broadband emission of self-trapping excitons (STE) for single emitters with soft lattices and local carriers, such as cesium copper halide, lead halide perovskite and lead-free double perovskite, has been investigated.These materials can be made into single crystal, bulk, two-dimensional and quantum dot (QD) states.However, their electroluminescence (EL) has not been extensively studied, especially for lead-free perovskites.Tang and colleagues pioneered the development of a warm white device based on bulk lead-free double perovskite Cs2 (Ag 0.6 Na 0.4) InCl 6, with a maximum brightness of 50 CD m−2. Shan and Coworker have demonstrated that only only lead can be applied to the device.The copper based terpolymer halide composite CsCu2I3@Cs3Cu2I5 has cold/warm white light tuning characteristics and corresponding WLED displays a maximum brightness of 145 CDM, an external quantum efficiency (EQE) of 0.15% and a high color rendering index (CRI) of 91.6.In this study, lead-free double perovskite CS2Agin 0.9Bi0.1Cl6 quantum dots were introduced into electrically excited quantum dot base WLEDs (QD-Wleds) as the emission layer for the first time.Lead-free double perovskite cs2Agin 0.9Bi0.1Cl6 quantum dots have strong dimensional reduction quantum confinement effect, STE emission in lead-free materials and superior stability of double perovskite structure.The QD WLEDs with competitive efficiency and brightness (EQE 0.08%, brightness 158 CD m−2) realize lead-free perovskite based devices under electric excitation.Encouragingly, the QD WLED obtained in the international Commission on Illumination (CIE) 1931 Color Space Map has a long working life (48.5 minutes T 50), a high CRI of 94.5, and a typical white light chroma coordinate of (0.32,0.32).Our study will provide new insights into the application of lead-free double perovskite quantum dots in lighting and display technologies.Figure 1.Morphology and crystal structure characterization of cs2Agin 0.9Bi0.1Cl6 quantum dots.Figure 2.Basic optical absorption and emission properties of CS2Agin 0.9Bi0.1Cl6 quantum dots.In figure 3.Cs2agin 0.9Bi0.1Cl6 based electroluminescent devices.This article is from the wechat public account “Materials Science and Engineering”.Welcome to reprint please contact, without permission declined to reprint to other sites.