Population growth and urbanization have stimulated demand for lighting, while the looming energy crisis has created challenges for people to use light. According to statistics, the global lighting electricity consumption accounts for about 20% of the total electricity consumption, and my country's lighting electricity consumption accounts for about 13% of the total power generation. Therefore, lighting has always been one of the key areas of energy conservation and low carbon at home and abroad. Recently, the research team of Zhengzhou University has made the latest progress in the field of green lighting.

According to the world lighting electricity statistics, in our country, electric lighting energy consumption has accounted for 25% of the average household energy budget. Therefore, under the background of the global energy crisis, energy conservation and environmental protection requirements, the development of green, high-efficiency, low-cost, and long-life solid-state lighting technology undoubtedly has important scientific significance and practical value.

At present, the most common strategy for preparing white solid-state light sources is to use blue LEDs to excite yttrium aluminum garnet phosphors to generate composite white light. However, the color rendering index of the white light illumination source prepared by this method is low, which cannot meet the application requirements of high-end lighting, and the phosphors contain relatively expensive strategic rare earth elements. Although white LEDs based on UV-pumped trichromatic phosphors can solve the problem of too low color rendering index, the self-absorption of various phosphors and the complicated preparation process bring new challenges to the device manufacturing cost and stability .

In this context, the development of single-component white light emitters is the key to solving the above problems. However, so far, few fluorescent materials with white light emission characteristics have been experimentally explored, and there is still a breakthrough in the preparation and application of high color rendering and high stability white light LEDs.

Recently, researchers have found that ns2 metal ion-based halides with strong electron-phonon coupling can form self-trapped excitons, resulting in efficient broadband light emission. Among the numerous ns2 metal ions, Sb3+ ions with unique singlet and triplet excitons exhibit blue and orange emission under different crystal field environments. Considering the strong dependence of ns2 ion emission on the crystal field environment, the selection of suitable host materials is expected to realize the generation of Sb3+ ion dual-band emission, thereby obtaining composite white light at room temperature.

In view of this, researchers from the School of Physics (School of Microelectronics), Zhengzhou University, using the vacancy-ordered double perovskite Cs2ZrCl6 as the host, adopted a facile ion doping technique to large-scale synthesis of single-component white light-emitting Cs2ZrCl6:xSb at room temperature (x = 0−8%), and successfully applied it to solid-state lighting.

By introducing Sb3+ ions with 5s2 activity into the thermodynamically stable Cs2ZrCl6 host, its special crystal field environment excites singlet and triplet dual-band emission (480nm@blue light, 580nm@orange light) originating from Sb3+ ions. Since there is an effective energy transfer channel between the singlet state and the triplet state, the degree of energy transfer between the singlet state and the triplet state can be quantified by controlling the doping concentration of Sb3+ ions, and the relative intensity changes of the two can be used to realize the cold and warm white light. tune. At a doping concentration of 1.5% Sb3+ ions, the material exhibits high-quality white light emission with a color rendering index of up to 96.

Further research found that with Cs2ZrCl6:1.5%Sb as the down-conversion phosphor, the prepared white LED showed a working life of 2003 hours. The above research results provide new ideas for the design and preparation of high color rendering and high stability single-component white light emitters.

Recently, the above research results were published in Nano Letters under the title "Regulating the Singlet and Triplet Emission of Sb3+Ions to Achieve Single-Component White-Light Emitter with Record High Color-Rendering Index and Stability". The first author of the paper is Zhang Fei, a 2020 doctoral student at the School of Physics, Zhengzhou University, and the corresponding authors are Professor Shi Zhifeng and Professor Shan Chongxin. This work was supported by the National Natural Science Foundation of China, the National Special Support Program for High-level Talents, the Science Fund for Distinguished Young Scholars in Henan Province, and the Innovative Team Program for Distinguished Young Talents of Zhengzhou University.