Xi'an Jiaotong University's dual packaging enhances the stability of all-inorganic perovskite LEDs

Solving the lighting stability challenges of perovskite white light-emitting diodes (WLEDs) is critical to their commercial viability. CsPbX3 (X = Cl, Br, I or mixed) nanocrystals (NCs) hold great promise in next-generation lighting due to their superior optical and electronic properties. However, the inherently soft material structure of CsPbX3 NCs is particularly susceptible to the high temperatures associated with long-term operation of WLEDs. In addition, these NCs also face stability challenges in high-humidity environments, resulting in reduced lighting performance.

Recently, the team of Professor Wang Minqiang of Xi'an Jiaotong University proposed a two-step dual-encapsulation method, and the obtained CsPbBr3@SiO2/Al2SiO5 composite fibers (CFs) have higher optical stability under extreme conditions. In tests, WLEDs assembled using these CFs maintained consistent electroluminescence (EL) intensity and brightness even when operated continuously at high power (100 mA) for a long time (9 hours) and when the surface temperature reached 84.2°C. Optoelectronic parameters. Crucially, the WLED maintained 97% of its initial fluorescence efficiency when left at 85°C and 85% relative humidity for 200 hours. These findings highlight the effectiveness of the dual-encapsulation strategy in significantly improving the stability of perovskite materials and mark an important step towards their commercial applications in optoelectronic lighting. The relevant results were published in small under the title "Stability Enhancement in All-Inorganic Perovskite Light Emitting Diodes via Dual Encapsulation".

Cesium lead halide perovskite CsPbX3 (X = Cl, Br, I or mixed) nanocrystals (NCs) are being developed due to their unique optoelectronic properties, including high photoluminescence quantum yields (PLQYs), tunable band gaps, and narrow emission. Becoming a potential candidate for the next generation of optical lighting materials. Despite these advantages, CsPbX3 nanomaterials are sensitive to environmental changes, especially high temperatures, which can significantly degrade their optical properties in even the smallest increments. Furthermore, exposure to high-humidity environments can cause partial decomposition of these NCs, negatively affecting fluorescence quality. In optoelectronic devices, long-term high-power operation produces high surface temperatures, which adversely affects the optical properties of the internal fluorescent materials. Therefore, improving the thermal stability of CsPbX3 nanomaterials is an important research direction in this field.

The authors of this article propose a new two-step encapsulation method to enhance the stability of CsPbBr3 nanocrystals. A highly translucent and waterproof SiO2 layer is used as the main encapsulation layer, and is subsequently encapsulated with high-temperature-resistant aluminosilicate composite fibers (Al2SiO5CFs) to obtain CsPbBr3@SiO2/Al2SiO5CFs, which exhibits good thermal and water stability. Subsequently, a two-step packaging method was used to obtain CsPbI3@SiO2/Al2SiO5 and CsPbCl3@SiO2/Al2SiO5CFs respectively, and a stable WLED device was assembled by adjusting the ratio of red, green and blue (RGB), which can operate continuously at high power (100 mA) after 9 h, the electroluminescence (EL) intensity and other optoelectronic parameters of the device had no significant changes. At this time, the surface temperature of the device had reached as high as 84.2°C. This excellent lighting stability perfectly meets the current market requirements for WLED devices and greatly improves the competitiveness of perovskite materials in the future commercial lighting field.