Dual Interfacial Hydrogen Bonds Enable Efficient Deep-Blue LEDs Based on a Hybrid Copper Iodide

Abstract Solution-processed light-emitting diodes based on non-toxic copper–iodide hybrids are a compelling solution for efficient and stable deep-blue lighting, attributed to their tunability, high photoluminescence efficiency, and environmental sustainability. Here we present a new hybrid copper iodide that exhibits near-unity photoluminescence quantum yield (99.4 ± 0.4%) with an emission wavelength of 449 nm and color coordinates (0.147, 0.087), alongside its emission mechanism and charge transport characteristics. We use the thin film of this hybrid as the sole active emissive layer (EML) to fabricate deep-blue LEDs and subsequently enhance the device performance via a unique dual interfacial hydrogen bond passivation strategy. This synergetic surface modification approach, integrating a new H-bond donor self-assembled monolayer with an ultra-thin PMMA capping layer, effectively passivates both heterojunctions of the copper–iodide hybrid EML and optimizes charge injections. We achieve a maximum external quantum efficiency of 12.57%, maximum luminance of 3970.30 cd m⁻² with color coordinates (0.147, 0.091), and an excellent operational stability (T₅₀) of 204 hours under ambient conditions. We further showcase a large-area device of 4 cm² that maintains high efficiency. Our findings reveal the potential of copper iodide-based hybrid materials for applications in solid-state lighting and display technologies, offering a versatile strategy for enhancing device performances.