Research Team of East China Normal University Achieves Highly Efficient and Bright Blue Perovskite LEDs

Metal halide perovskites have emerged as promising luminescent materials for next-generation display technologies owing to their excellent color purity, wide color gamut, high photoluminescence quantum yields (PLQYs), and cost-effective solution processability. Realizing highly efficient and bright perovskite light-emitting diodes (PeLEDs) is critical for advanced full-color displays, especially near-eye displays such as augmented reality (AR), virtual reality (VR) and mixed reality (MR). Despite recent research breakthroughs enabling green and red PeLEDs to simultaneously achieve external quantum efficiencies (EQEs) exceeding 30% and high luminance above 10,000 cd m, the comprehensive performance of blue PeLEDs still falls far behind.

The performance limitations of blue PeLEDs stem not only from the inherent drawbacks of wide-bandgap perovskite materials, but more importantly, from the intrinsic fragility of the buried bottom interface in devices. Serving as physical channels for charge injection and substrates for grain growth, the stability of the buried bottom interface directly governs interfacial charge dynamics and the crystallization process of perovskites. Poly(9-vinylcarbazole) (PVK), a widely adopted hole transport layer (HTL) beneath the perovskite layer, possesses favorable hole-transporting properties and is extensively employed in current blue-emitting device architectures. Nevertheless, the linear molecular structure of this polymeric HTL bears intrinsic structural vulnerability. When directly exposed to aprotic polar solvents used in perovskite precursor solutions, it tends to swell and dissolve. Such structural instability further results in poor film coverage, severe pinhole formation and energy level misalignment, which trigger increased leakage current, unbalanced carrier injection and high-density trap states. These factors constitute the fundamental constraints on the electroluminescence (EL) performance of blue PeLEDs.

Previous studies have attempted to mitigate these issues via interfacial engineering approaches. For instance, introducing the [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2-PACz) self-assembled monolayer at the inorganic nickel oxide (NiO?)/PVK heterointerface can strengthen interfacial adhesion by forming tridentate coordination bonds with NiO? and effectively passivate surface trap states of NiO?, thus helping improve the EL performance of blue PeLEDs. However, these mainstream interfacial engineering strategies focus on static optimization of energy level alignment and interfacial bonding, yet fail to dynamically suppress solvent erosion toward the PVK layer during perovskite film deposition. The penetration and swelling of polar solvents within linear polymer matrices induce interfacial morphology collapse and concomitant degradation of electrical performance, which acts as a fundamental bottleneck in current device architectures. Therefore, developing integrated interfacial strategies that can simultaneously maintain physical integrity, realize effective chemical passivation and enable precise energy level modulation remains a core task to advance high-performance blue PeLEDs.

Li Yanqing from East China Normal University, Tang Jianxin and Yang Shen from Soochow University and co-workers propose an interfacial engineering strategy utilizing a three-dimensional crosslinked network derived from pentaerythritol tetraacrylate (PETA) to construct highly efficient and bright blue perovskite LEDs (Figure 1). Compared with conventional linear polymers, this thermally crosslinked 3D network delivers unique advantages in interface regulation. Benefiting from outstanding solvent resistance, the crosslinked network forms a robust physical barrier that efficiently protects the underlying PVK layer from erosion during the solution processing of perovskites. Furthermore, abundant carbonyl groups within the crosslinked network establish stable coordination interactions with the perovskite lattice, effectively passivating interfacial defects and enhancing heterojunction stability. Meanwhile, charge transfer between PVK and polymerized PETA generates interfacial dipoles, elevating the work function of the PVK layer and facilitating hole injection. By implementing this strategy, efficient blue emission is achieved. The resulting PeLEDs yield EQEs of 28.0%, 21.3% and 15.4% at 488 nm, 476 nm and 466 nm, with maximum luminance reaching 26,240, 10,750 and 2,444 cd m??, respectively, representing state-of-the-art performance among reported blue PeLEDs.