2D Mixed Halide Perovskites for Ultraviolet Light-emitting Diodes

Advances in perovskite light-emitting diodes (PeLEDs) have established them as viable candidates for next-generation displays and lighting across the entire visible spectrum, with recent investigations extending their emissive properties into the deep blue and violet regions. These materials have the potential to overcome the fabrication complexities inherent in conventional III-V semiconductors by circumventing the necessity for lattice-matching, instead allowing for straightforward deposition of polycrystalline films without relying on metal-organic chemical vapor deposition. However, achieving shorter emission wavelengths presents a significant challenge due to the larger bandgaps required of both the perovskite and charge transport materials, compounding the difficulty in managing electron-hole pair recombination dynamics necessary for efficient electroluminescence. In this work, we address these challenges by precisely tuning the halide composition in two-dimensional perovskites, successfully extending the bandgap to 3.1 eV and achieving photoluminescent emission at 393 nm. By introducing an optimized dual electron transport layer architecture, we improve electron injection and hole confinement within the perovskite matrix, culminating in a high-purity electroluminescent emission at 399 nm. This strategy yields a maximum external quantum efficiency of 0.16%, a new benchmark for PeLEDs operating in this spectral domain. These findings highlight the potential of large bandgap perovskite materials for next-generation light-emitting applications.