Recently, Professor Wang Ning's team from the School of Physics of Jilin University has made important progress in the research of large-area perovskite LEDs. The relevant results were published in the international academic journal "Laser & Photonics Reviews" under the title "Efficient and stable perovskite LED prepared by the regulation of vertical spatial crystallization dynamics".

As an emerging light-emitting technology, quasi-two-dimensional perovskite light-emitting diodes (Q-2D PeLEDs) have attracted much attention due to their excellent optoelectronic properties. In recent years, the external quantum efficiency of Q-2D PeLEDs has made rapid progress, demonstrating its great potential as a next-generation optoelectronic device. However, most of these advances are limited to small-area devices in the laboratory, usually at the square millimeter level, and achieving large-area high-efficiency devices is still an unavoidable challenge. Therefore, how to prepare efficient and stable large-area Q-2D PeLEDs has become a key problem for future full-color display and solid-state lighting applications.

Based on this, this work proposes a sodium bromide (NaBr) assisted crystallization method, which can effectively regulate the top-down crystallization process of Q-2D perovskite films and precisely regulate the phase distribution of the film in the vertical space. In addition, the strong interaction between Na+ and PbBr64- plays a key role in passivating surface bromine vacancy defects and inhibiting non-radiative recombination.

Not only that, due to the presence of Na+, it partially replaces the organic ligands on the surface of the film, significantly reducing the content of organic ligands and improving the carrier transport capacity of the device. Finally, the external quantum efficiency (EQE) of the device reached 26.5%. Even if the effective area of the device is expanded by more than 200 times, the efficiency can still reach 18.3%.

In addition, the passivation of defects and the improvement of carrier transport capacity also significantly enhance the operating stability of the device. At an initial brightness of 100 cd/m2, the operating half-life (T50) of small-area and large-area devices is as high as 612 hours and 112 hours, respectively. This breakthrough has brought new references for the large-scale application of perovskite light-emitting diodes, and is expected to be widely used in full-color display and solid-state lighting in the future.