image: Figure | (Title) EL performance of CsPbBr3 NPL based PeLEDs. a, Schematic illustration of the device architecture. b, Cross-sectional SEM image of the PeLED. c, Two-dimensional plot of the EL spectra under varying driving voltages. d, Current density-voltage-luminance characteristics. e, EQE versus current density for PeLEDs. The inset shows a photo of the PeLED at a voltage of 7.5 V. f, Comparison of EQE versus CIE-y values for representative blue PeLEDs.
Credit: Sheng Cao et al.
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 CsPbBr3 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 Pb2+ ions. This approach significantly improved both the passivation effectiveness and the structural integrity of CsPbBr3 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 CsPbBr3 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.”
Journal
Light Science & Applications
Article Title
Efficient deep-blue LEDs based on colloidal CsPbBr3 nanoplatelets meeting the Rec.2020 standard