Scientists have developed a one-component warm white photoluminescent device

Recently, Associate Professor Yang Bin of the Reaction Kinetics Research Group of Complex Molecular Systems (Group 1101) of our Institute cooperated with Feng Liu of Shandong University to develop a new double perovskite material with efficient white light emission, and prepared a one-component warm white light-emitting diode (LED) based on this material.

Electric lighting accounts for 15% of global electricity consumption and releases 5% of the world’s greenhouse gases. The use of more efficient and low-cost lighting technology can alleviate the energy and environmental crises and help achieve the “dual carbon” goal. At present, the vast majority of white LED technology mainly relies on blue LED excitation multi-component fluorescence superposition to produce white light, so it is easy to have problems such as poor color rendering, low luminous efficiency, high harmful blue light components, and discontinuous white light spectrum. The development of efficient one-component white light materials is considered to be the key to solving these problems.

The researchers found that non-lead metal halide double perovskite materials can be prepared by low-temperature solution method with low production cost. In addition, due to the limitation of its own structure and the strong electro-phonon coupling effect, the double perovskite material has a unique self-trapping exciton characteristic (STE), and its composite luminescence shows a large Stokes shift and broadband light emission, thus showing the characteristics of white light emission. In this work, researchers prepared a one-dimensional structure (DFPD) 2MIInX6 (MI= K, Rb) with a one-dimensional structure by using strong chemical bonds between organic molecules 4, 4-difluoropiperidine (DFPD) and alkali metals; X = Cl, Br) double perovskite compound. Among them, DFPD+ not only acts as an effective interlayer spacer to balance the charge, but also as a key component in the formation of metal halide octahedron. In particular, the electron state in (DFPD)2MIInX6 is spatially confined to a single octahedron, producing a natural electron confinement effect. To promote radiation recombination, the researchers further employed a micro Sb3+ doping strategy to increase the white light quantum efficiency from 5% to more than 90%. Due to the high optoelectronic performance and excellent solution processability of the prepared low-dimensional double perovskite material, one-component warm white LEDs based on the material can be prepared by simple solution method, so this work provides new ideas for the design of next-generation lighting devices.

In recent years, Yang Bin et al. have carried out systematic research in the field of self-trapping exciton-based one-component white light materials and their luminescence dynamics: the ultrafast self-trapping process of excitons was revealed (Angew. Chem. Int. Ed.,2019;Acc. Chem. Res., 2019), and the mechanism of electrophonon coupling on this ultrafast process (Sci. Bull., 2020); revealed the luminescence mechanism based on self-trapping exciton heat-activated delayed fluorescence (Angew. Chem. Int. Ed., 2020); efficient white light emission in colloidal nanocrystals was realized through efficient energy transfer between the trilinear self-trapping exciton and the acceptor ion Mn2+ (Nano Lett., 2021); and expanded its role in long-afterglow luminescent materials based on the unique properties of self-trapping excitons (Angew. Chem. Int. Ed., 2022), highly sensitive ultraviolet photodetector (Adv. Mater., 2021; Laser Photonics Rev., 2022), X-ray scintillators (J. Phys. Chem. Lett.,2022;J. Phys. Chem. Lett., 2022; Laser Photonics Rev., 2022), ultra-sensitive optical thermometer (J. Phys. Chem. Lett., 2022) and other applications.

The research results were published in German Journal of Applied Chemistry under the title “Highly Luminescent One-Dimensional Organic–Inorganic Hybrid Double-Perovskite-Inspired Materials for Single-Component Warm White-Light-Emitting Diodes” (Angewandte Chemie International Edition). The first author of this work is Bai Tianxin, a doctoral student jointly trained by the 1101 group of our institute. The above work has been supported by the National Natural Science Foundation of China, the Youth Promotion Association of the Chinese Academy of Sciences, and the Innovation Fund of our institute. (Source: Dalian Institute of Chemical Physics, Chinese Academy of Sciences)

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