Efficient and High-Conductivity Perovskite LEDs with Low Operating Voltage

Lead halide perovskites are promising materials for high-performance light-emitting diodes (LEDs) owing to their optoelectronic properties, including high photoluminescence quantum yield (PLQY), tunable bandgap, and outstanding charge carrier mobility. Despite rapid progress, achieving high luminance at a low operating voltage remains a major challenge for perovskite LEDs (PeLEDs), largely due to limited carrier injection in conventional device architectures. Here, we present a synergistic strategy to realize low-voltage, high-efficiency PeLEDs. The device integrates a [2-(3,6-dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid (Br-2PACz) self-assembled monolayer, a compact three-dimensional (3D) perovskite emissive film, and a zinc oxide (ZnO) electron transport layer (ETL). Sulfobetaine 10 (SFB) is employed to regulate crystallization, leading to dense and uniform perovskite films with reduced trap density. The Br-2PACz interlayer simultaneously passivates interfacial defects, facilitates hole injection, and suppresses electron leakage by tuning the energy levels. In addition, the high-mobility ZnO ETL ensures efficient electron injection. The optimized PeLED exhibits a low turn-on voltage of 1.9 V and achieves a luminance of 39,000 cd m^-2 and a current density of 38.5 mA cm^-2 at 2.5 V. The device delivers a peak external quantum efficiency (EQE) of 22.5% and a peak power efficiency (PE) of 128.7 lm W^-1. Moreover, this strategy demonstrates good scalability: large-area PeLEDs (1600 mm²) retain a competitive EQE of 11.2% with uniform emission. This work supplements the research on energy-efficient, low-voltage-operating, and scalable PeLEDs.