Composition engineering to obtain efficient hybrid perovskite light-emitting diodes
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RESEARCH ARTICLE
Composition engineering to obtain efficient hybrid perovskite light-emitting diodes Chuanzhong YAN*, Kebin LIN*, Jianxun LU, Zhanhua WEI (✉) Institute of Luminescent Materials and Information Displays, College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, China
© Higher Education Press 2020
Abstract Metal halide perovskites have received considerable attention in the field of electroluminescence, and the external quantum efficiency of perovskite lightemitting diodes has exceeded 20%. CH3NH3PbBr3 has been intensely investigated as an emitting layer in perovskite light-emitting diodes. However, perovskite films comprising CH3NH3PbBr3 often exhibit low surface coverage and poor crystallinity, leading to high current leakage, severe nonradiative recombination, and limited device performance. Herein, we demonstrate a rationale for composition engineering to obtain high-quality perovskite films. We first reduce pinholes by adding excess CH3NH3Br to the actual CH3NH3PbBr3 films, and we then add CsBr to improve the crystalline quality and to passivate nonradiative defects. As a result, the (CH3NH3)1 – xCsxPbBr3 based perovskite light-emitting diodes exhibit significantly improved external quantum and power efficiencies of 6.97% and 25.18 lm/W, respectively, representing an improvement in performance dozens of times greater than that of pristine CH3NH3PbBr3-based perovskite light-emitting diodes. Our study demonstrates that composition engineering is an effective strategy for enhancing the device performance of perovskite light-emitting diodes. Keywords perovskite, light-emitting diode (LED), composition engineering, ion doping
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Introduction
Recently, metal halide perovskite materials have received considerable attention in the field of light-emitting diodes Received May 18, 2020; accepted June 30, 2020 E-mail: [email protected] *
These authors contributed equally to this work.
(LEDs). Perovskite materials have unique advantages, such as high photoluminescence quantum yields (PLQYs), excellent color purity, high defect tolerance, tunable bandgap, wide color gamut, and low cost [1–6]. The first room-temperature operative perovskite light-emitting diodes (Pero-LEDs) were reported by Friend et al. in 2014 [1]. They used three-dimensional (3D) perovskite materials of MAPbI3–xClx (MA:CH3NH3+) and MAPbBr3 as the light-emitting layer to prepare near-infrared and green LED devices, the corresponding external quantum efficiencies (EQEs) of which were 0.76% and 0.1%, respectively [1]. To date, tremendous research progress has been accomplished in the fabrication of multicoloremitting Pero-LEDs and improving their performance [7–14]. In particular, the EQE values of green [15], visible red [16], and near-infrared [17–19] region Pero-LEDs have drastically increased to over 20%. Pero-LEDs have exhibited promising application prospects in the fields of flat displays and solid lighting [20,21]. The chemical formula of metal halide perovskite is generally of the form ABX3, where A is a monovalent
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