Copper-Iodide Hybrid Clusters with Partial Distortion Enable High-Performance Full-Visible-Spectrum White-Light-Emitting Diodes

Phosphor-converted white-light-emitting diodes (pc-WLEDs) have become increasingly prevalent artificial light sources. Currently, multicomponent phosphors are commonly used for pc-WLEDs, but they often suffer from issues of undesirable reabsorption and unstable emission colors. The potential alternative for pc-WLEDs is a single-component white phosphor that covers the broad visible spectrum with desirable low thermal quenching and efficient luminescence, which is still scarce. To address this challenge, we design a unique single-component white phosphor based on Cu₄I₄(4-(<i>tert</i>-butyl)-2-(diphenylphosphaneyl)pyridine)₂ (Cu₄I₄(NP-^<i>t</i>Bu)₂) hybrid clusters, which exhibits ultrabroad dual emission from 400 to 800 nm and a high photoluminescence quantum yield of 97% under 320 nm light excitation. Based on time-resolved fluorescence spectroscopy and theoretical model analysis of our Cu₄I₄ series clusters, we hypothesize that the dual emission comes from the coexistence of two triplet states caused by partial cluster distortion under light excitation. The Cu₄I₄(NP-^<i>t</i>Bu)₂ cluster's high structural stability also endows consistent spectral performance and low thermal quenching up to 240 °C. Thus, the fabricated pc-WLED using Cu₄I₄(NP-^<i>t</i>Bu)₂ white phosphor exhibits a maximum efficiency of 63.4 lm/W and maintains a high color rendering index of ∼88 during 1000 h of continuous operation. Our results highlight a new strategy of low-cost and high-performance copper-iodide cluster-based single-component white phosphors for high-quality pc-WLEDs.