Overcoming Efficiency Limitation of Cluster Light-Emitting Diodes with Asymmetrically Functionalized Biphosphine Cu4I4 Cubes

Electroluminescent (EL) nanoclusters holding promise for new-generation cluster light-emitting devices (CLEDs) rapidly emerge. However, slowradiation and serious quenching of cluster emitters largely limit the deviceperformance. Herein, we report two monofunctionalized biphosphine chelatedCu4I4clusters [DMACDBFDP]2Cu4I4and [DPACDBFDP]2Cu4I4. The asymmetricmodification and electron-donating effect of acridine groups lead to the iodine-to-ligand charge transfer predominant excited states of the clusters, which featurethermally activated delayedfluorescence with markedly improved singlet radiative rateconstants and reduced triplet nonradiative rate constants. As consequence, comparedto the nonfunctionalized parent cluster, [DPACDBFDP]2Cu4I4achieves 16-foldincreased photoluminescence (81%) and 20-fold increased EL (19.5%) quantumefficiencies.Such new-record efficiencies make CLEDs achieve the state-of-the-artperformance of all kinds of EL technologies.

Automated summary

This study reports two new modification methods to improve the luminous efficiency of electroluminescent (EL) nanoclusters. These modifications result in higher photoluminescence and electroluminescence efficiencies, achieving new performance records for CLEDs in various EL technologies.