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    Technical breakthrough! Researchers use unstable perovskites to make blue LEDs
    Hits:   Date:2020-05-26  
    According to reports, scientists from the University of California, Berkeley (UC Berkeley) used a new type of halide perovskite semiconductor material to produce blue LEDs, overcoming the application of these cheap and easy-to-manufacture materials to electronic devices The main obstacles facing China.

    It is reported that the research results were published on Science Advances, a sub-journal of Science, on January 24, demonstrating technological breakthroughs made in the application of unstable halide perovskites. The main reason is that it will change with temperature, humidity and chemical environment, thereby destroying its optical and electronic properties.

    Yang Peidong, a professor in the Department of Chemistry at the University of California, Berkeley, who is responsible for this research, said that manufacturing blue-emitting semiconductor diodes has always been a challenge. So far, red and green LEDs made from perovskite have been confirmed, while blue LEDs have not. The halide perovskite blue LED has been unstable mainly because its color will change to longer and redder wavelengths with use.

    The study found that the instability of the halide perovskite is caused by the unique nature of the perovskite crystal structure, which is composed of metals and halogen atoms. When these elements are mixed together in a solution and then dried, the atoms form a crystal. Nitride Powder. Chemists at the University of California, Berkeley and the Berkeley Lab used a new technology and cesium, lead, and bromine to create blue-emitting perovskite crystals.

    At the same time, the team also found that the light emitted by these crystals depends on the arrangement of the atoms and the distance between the atoms, and the color changes with temperature. For example, a perovskite crystal that emits blue light (wavelength 450 nm) at a temperature of 300 Kelvin can suddenly emit blue-green light at 450 Kelvin.

    Professor Yang Peidong said that the characteristics of blue perovskite color change with temperature can bring interesting applications. Two years ago, he showed a window made of halide perovskite, which becomes dark in the sun and becomes transparent when the sun goes down, and can also produce photovoltaic energy.