Perovskite light-emitting diodes (PeLEDs) are widely regarded as promising candidates for next-generation display technologies due to their outstanding color purity and high luminous efficiency. While red and green PeLEDs have already achieved external quantum efficiencies (EQEs) exceeding 20%, progress in deep-blue devices has been hindered by strict performance requirements. The Rec.2020 color standard set by the International Telecommunication Union requires extremely pure blue emission (CIE-y ≤ 0.046), a benchmark that conventional mixed-halide perovskites have struggled to meet due to halogen vacancies and phase segregation.
To address this challenge, a research team led by Professors Sheng Cao, Jialong Zhao, and Bingsuo Zou at the State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures, Guangxi University, together with collaborators, has reported a major breakthrough in Light: Science & Applications . They developed efficient deep-blue PeLEDs based on colloidal CsPbBr 3 nanoplatelets (NPLs), enabled by an acid-assisted ligand passivation strategy. The team achieved a photoluminescence quantum yield of 96% and narrow-band emission with a full width at half maximum of just 13 nm. As a result, the fabricated PeLEDs delivered record-breaking performance: a maximum EQE of 6.81% at 461 nm and precise color coordinates (CIE-y = 0.046) that fully satisfy the stringent Rec.2020 requirement.
The key innovation lies in exfoliating long-chain organic ligands with hydrobromic acid and forming robust Pb-S-P coordination bonds between thio-tributylphosphine (S-TBP) and surface Pb 2+ ions. This approach significantly improved both the passivation effectiveness and the structural integrity of CsPbBr 3 NPLs. As a result, the devices not only achieved record efficiency but also showed stable deep-blue emission that complies with Rec.2020.
Further insights were provided by density functional theory (DFT) calculations and experimental validation. Compared with common long-chain ligands oleic acid and oleylamine, the short-chain S-TBP ligand exhibited a much higher adsorption energy (-1.13 eV), leading to stronger surface anchoring and enhanced environmental stability while maintaining the intrinsic quantum confinement effect. The passivated CsPbBr 3 NPLs preserved stable CIE coordinates in both solution and solid film under ambient conditions, while effectively suppressing trap-assisted non-radiative recombination.
“This work provides an effective strategy for achieving efficient and stable deep-blue PeLEDs,” the authors noted. “It highlights the strong potential of perovskite nanomaterials for commercialization in next-generation ultra-high-definition display technologies.”
Light Science & Applications
Efficient deep-blue LEDs based on colloidal CsPbBr3 nanoplatelets meeting the Rec.2020 standard