Nankai University breaks perovskite white LED performance record

On March 11, the top international academic journal Nature Photonics published online the latest research results of a research team led by Professor Yuan Mingjian and Researcher Jiang Yuanzhi from the School of Chemistry at Nankai University.

The team has made significant progress in the field of new perovskite full-color ultra-high-definition display technology and successfully developed a high-performance red, green, and blue triple-junction white light perovskite LED, which can be applied to the next generation of high-color gamut backlight sources and ultra-high-definition displays.

It is reported that perovskite LEDs rely on their extremely high color purity and flexible adjustable wavelength characteristics. However, to achieve high-quality white light display, it is usually necessary to vertically stack red, green, and blue light-emitting units. In the traditional preparation process, the solution processing method can easily cause solvent damage to the underlying material, seriously weakening the efficiency and stability of the device.

Although transfer printing technology has had high hopes, the traditional transfer printing process often destroys the film structure due to excessive interfacial adhesion, resulting in significant performance degradation. In response to this core pain point, a research team from Nankai University innovatively proposed a new strategy for solid-liquid switchable interfaces. By introducing an ammonium carboxylate intermediate layer that can controlly release methylamine, the team achieved instantaneous liquefaction of the perovskite surface during the transfer process. This design significantly reduced the adhesion and mechanical stress between the interfaces, allowing the transferred film to completely reach the level of the original spin-coated film in terms of morphology and photoelectric properties, achieving lossless integration.

In terms of device structure design, the research team constructed a high-efficiency sub-unit connection layer based on lithium fluoride, gold and molybdenum trioxide. Through precise interface dipole control and tunneling-assisted injection mechanism, the charge generation barrier was successfully minimized, and the total voltage loss was only about 0.5 volts.

Thanks to the lossless transfer process and optimized interconnect structure, the all-perovskite triple-junction white LED device has a maximum brightness of 67,370 candelas per square meter, a peak external quantum efficiency of 17.6%, and a color gamut coverage that reaches 143% of the NTSC standard, surpassing all previously reported perovskite-based tandem white LED records.

The research team stated that the transfer integration strategy not only improves the efficiency and color gamut performance of perovskite LEDs, but also demonstrates the potential for large-scale production. Experimental results show that the process has good compatibility on both rigid glass and flexible polymer substrates. At present, the team has successfully developed a backlight display prototype, which has initially verified the feasibility of this technology from the laboratory to engineering.