White LED lamp beads (light-emitting diodes) are an important part of lighting and display applications, but these two application areas consume a lot of power energy, so the realization of high-efficiency white LEDs is of great significance for energy conservation and emission reduction. After the development of science and technology in recent years, metal halide perovskite LEDs have shown great potential and are likely to become a new generation of light-emitting technology.

    Among them, the external quantum efficiency of red and green perovskite LEDs has rapidly increased from less than 1% to more than 20%, and the efficiency of blue perovskite LEDs has also exceeded 12%, but the development of perovskite white light devices is still very high. slow. Based on optical simulation analysis, in traditional perovskite LED devices, more than 80% of the photons are limited in the device and cannot be emitted, so that the light extraction efficiency of perovskite LEDs is generally less than 20%, which has become another constraint to its further development. The key issue.

    In response to the above scientific problems, the team proposed a simple and effective method to simultaneously solve the problems of limited light extraction efficiency and low performance of white light devices in perovskite LEDs, namely by rationally designing multilayer semitransparent electrodes (LiF/ Al/Ag/LiF), to couple the blue light perovskite layer with the red light perovskite nanocrystalline layer in the near-field to achieve a substantial increase in the light extraction efficiency, thereby constructing a high-performance white light perovskite LED device.

    Due to the large difference between the refractive index of the perovskite light-emitting layer and the refractive index of the organic interface layer, total reflection will be caused at a specific angle, which induces an optical waveguide mode in the perovskite LED device, making the part emitted by the light-emitting layer. The photons oscillate repeatedly inside the device without escaping outside the device. The evanescent waves generated during total reflection will continue to induce the generation of surface plasmon polariton (SPP) modes.