Enhanced Operational Stability of Carbene‐Metal‐Amide Organic Light‐Emitting Diodes by Reducing Electron Accumulation on the Emitter

Carbene‐metal‐amide (CMA) complexes are promising emitters due to their triplet‐harvesting properties combined with submicrosecond emission lifetimes. In spite of this, CMA‐based organic light‐emitting diodes (OLEDs) suffer from poor operational stability. Here, it is demonstrated for a prototypical blue CMA emitter that the poor stability is the result of a combination of low bond‐dissociation energies in the anionic state and poor electron transport, the latter leading to electron accumulation on the emitter. To eliminate this degradation pathway, an electron‐transporting host is used, which reduces electron occupation of the emitter and simultaneously increases electron transport. As a result, efficient and stable single‐layer OLEDs are achieved, exhibiting external quantum efficiencies (EQEs) above 20% and LT 50 lifetimes of 120 h at 1000 cd m − 2 , the longest lifetime reported for blue CMA OLEDs to date. The enhanced stability arises from reduced bond cleavage of the emitter in the anionic state and a broadened recombination zone by virtue of the single‐layer OLED architecture. These results establish a framework for overcoming intrinsic degradation pathways in CMA emitters, unlocking their potential for practical OLED applications and guiding future advances in stability.