Efficient deep-blue LEDs based on colloidal CsPbBr3 nanoplatelets meeting the Rec.2020 standard
Yusheng Song, Sheng Cao, Yijie Wang, Mingyan Chen, Yù Zhang, Qiuyan Li, Shulin Han, Yi Liang, Lei Cai, Jialong Zhao, Bingsuo Zou
Abstract
Abstract Colloidally quantum-confined CsPbBr 3 nanoplatelets (NPLs) exhibit narrow emission linewidths and thickness-tunable photoluminescence, making them ideal candidates for deep-blue perovskite light-emitting diodes (PeLEDs). However, the weak surface coordination of conventional long-chain ligands ( e.g ., oleylamine and oleic acid) leads to face-to-face stacking of the NPLs, resulting in undesirable emission redshifts in their PeLEDs. Herein, we report an efficient deep-blue PeLED based on colloidal CsPbBr 3 NPLs that meet the Rec.2020 color standard, enabled by an acid-assisted ligand passivation strategy. Surface chemical analysis reveals that hydrobromic acid facilitates proton-assisted stripping of the long-chain ligands, followed by the formation of stable Pb-S-P coordination bonds with thio-tributylphosphine, which exhibits a high adsorption energy (E ads = -1.13 eV). This approach significantly improves surface defect passivation, yielding a photoluminescence quantum yield of 96% and a narrow 13 nm full-width-at-half-maximum deep-blue emission. Enhanced exciton recombination and reduced defect state density are evidenced by a prolonged photoluminescence lifetime and slower absorption bleach recovery kinetics. The resulting PeLEDs achieve record-breaking performance among CsPbBr 3 NPL-based systems, with a maximum external quantum efficiency of 6.81% at 461 nm, a peak luminance of 143 cd m -2 , and the CIE color coordinates (CIE-y = 0.046) that comply with Rec.2020 standards. This work presents an effective strategy for developing efficient and stable deep-blue perovskite emitters, demonstrating significant potential for the commercialization of perovskite nanomaterials in next-generation ultra-high-definition displays.