Recently, Guangxi University's nanophotonics research team made new advancements in the field of deep-blue LEDs. The findings, titled "Efficient deep-blue LEDs based on colloidal CsPbBr₃ nanoplatelets meeting the Rec.2020 standard," were published in Light: Science & Applications, a subsidiary journal of Nature. The lead author is Song Yusheng, a 2023 doctoral student from the School of Physical Science and Technology, with corresponding authors Prof. Dr. Cao Sheng, Prof. Dr. Zhao Jialong from the same school, and Prof. Dr. Zou Bingsuo from the School of Resources, Environment and Materials. Guangxi University is the primary and corresponding affiliation.  

Lead is a key characteristic metal in Guangxi, abundant in resources and often coexisting or associated with other critical metals such as tin and antimony in minerals. In recent years, as a core element of novel ionic semiconductors--halide perovskite materials--it has demonstrated exceptional performance in optoelectronic technology. Perovskite light-emitting diodes (PeLEDs) are considered ideal candidates for next-generation displays due to their excellent color purity and high luminescent efficiency. Although the external quantum efficiency (EQE) of red and green PeLEDs has exceeded 20%, the development of deep-blue PeLEDs remains challenging. The International Telecommunication Union's Rec.2020 standard imposes stringent requirements for blue color coordinates (CIE-y≤0.046). However, conventional mixed-halide perovskites struggle to achieve both high efficiency and color purity due to halogen vacancy defects and phase separation. Colloidal CsPbBr3 nanoplatelets (NPLs), leveraging quantum confinement effects and anisotropic bandgap tunability, enable narrow-band deep-blue emission and are regarded as an ideal material to address this issue. Nevertheless, surface defects and ligand instability still cause severe non-radiative recombination, limiting further enhancement of their LED device performance.

To address this challenge, the research team developed an innovative acid-assisted ligand passivation strategy to modify the synthesis route, successfully producing CsPbBr3 NPLs with significantly enhanced luminescent properties. This method utilizes proton interactions to remove weakly bound long-chain ligands (oleylamine and oleic acid) and introduces short-chain tributylphosphine-sulfur (S-TBP) for efficient passivation, boosting the material's photoluminescence quantum yield from 19% to 96%. The emission peak remains stable at 461 nm, with a full width at half maximum of only 13 nm and a CIE-y value as low as 0.046. The deep-blue PeLED constructed from this material achieved an EQE of 6.81% and a peak brightness of 143 cd/m², setting new benchmarks for key performance metrics in this field. This achievement provides an effective strategy for developing efficient and stable deep-blue PeLEDs, highlighting the promising potential of perovskite nanomaterials for commercialization in next-generation ultra-high-definition displays.  

This research was supported by the National Natural Science Foundation of China, Guangxi Science and Technology Program, Guangxi "Nanophotonics Materials and Technology" Talent Highland Initiative, and the National and Regional Key Laboratories for Nonferrous Metals and Special Processing.