Allochroic cluster light-emitting diodes based on unique μ 3 -tetraphosphine Cu 3 X 3 crowns with tunable excited states

Abstract

Multicomponent excited states endow copper iodide clusters with allochroic properties under diverse stimuli. However, crystal states are required, and cluster stimulus sensitivity hampers electroluminochromism. We developed PhQPCu 3 X 3 (X = Cl, Br, and I) with the first μ 3 -bridging tetraphosphine ligand, whose Cu 3 X 3 crowns were exposed to external stimulus. The increased proportion of Cu 3 X 3 results in equal contributions of cluster- and ligand-centered components to excited states, the former of which is highly sensitive to grind, vapor, and, especially, electric stimuli, due to semi-exposed Cu 3 X 3 . Through vacuum evaporation and vapor fumigation of cluster-based emissive layers, the diodes' electroluminescence colors changed from yellow to white. Joule heat during device operation induced further color variation to orange, corresponding to Commission Internationale de l’Eclairage coordinates of PhQPCu 3 I 3 changed from (0.44 ± 0.1, 0.34 ± 0.1) to (0.57 ± 0.1, 0.42 ± 0.1). These results demonstrate the superiority of luminescent clusters in accurate excited-state modulation, holding promise for wide applications.