Harnessing of Cooperative Cu⋅⋅⋅H Interactions for Luminescent Low‐Coordinate Copper(I) Complexes towards Stable OLEDs

Abstract Although two‐coordinate Cu(I) complexes are highly promising low‐cost emitters for organic light‐emitting diodes (OLEDs), the exposed metal center in the linear coordination geometry makes them suffer from poor stability. Herein, we describe a strategy to develop stable carbene‐Cu‐amide complexes through installing intramolecular noncovalent Cu⋅⋅⋅H interactions. The employment of 13H‐dibenzo[a,i]carbazole (DBC) as the amide ligand leads to short Cu⋅⋅⋅H distances in addition to the Cu−N coordination bond. The resultant Cu(I) complexes exhibit yellow thermally activated delayed fluorescence with photoluminescence quantum yields of up to 86 % and radiative decay rate constants on the order of 106 s−1. Comparing with the analogues without Cu⋅⋅⋅H interactions, the pincer complexes have significantly improved stability. The vacuum‐deposited OLEDs show high‐performance electroluminescence with maximum external quantum efficiencies of up to 29.5 % and extremely small roll‐offs of only 3.5 % at 10,000 cd m−2. Remarkably, the operational lifetimes (LT90) are up to 68 h with an initial luminance of 3000 cd m−2. This work proves a feasible design of robust low‐coordinate metal complexes by leveraging secondary coordination interactions, which helps to overcome the long‐standing stability problem.