Authors
Shuo Xu, Rui Tang, Qingyun Wan, Gang Cheng, Jun Yang, Chi-Ming Che
Published in
Advanced science (Weinheim, Baden-Wurttemberg, Germany). Pages e00075. Jun 29, 2026. Epub Jun 29, 2026.
Abstract
Luminescent d10 carbene-metal-amide (CMA) complexes are a promising class of thermally activated delayed fluorescence (TADF) organic light-emitting diode (OLED) emitters. However, the principles for modifying ligands to maximize OLED efficiency and operational stability remain unclear. Here, we reveal the key role of metal (n+1)p-nd orbital hybridization and excited-state metal-ligand π-interactions in affecting the excited-state stability and electro-/photoluminescence efficiency of CMA emitters. Using density functional theory (DFT), high-level coupled cluster singles and doubles (CCSD) method, and combined DFT and multireference configuration interaction (DFT/MRCI) calculations, we found that in the excited state, metal atoms and carbazole nitrogen atoms form π-interactions, which is weakened by the weakening of metal (n+1)p-nd orbital hybridization. The weakened metal-nitrogen (M─N) π-interaction is conducive to more flexible rotation of the excited-state dihedral angle, thereby increasing the radiative decay rate (kTADF). This rationalizes the general trend of kTADF for CMA emitters: Ag > Au > Cu. However, the weakening of the excited-state M─N π-interaction reduces the strength of the M─N bond and facilitates bond dissociation in the excited state, thereby impairing the stability of the emitter. Our calculations show that introducing electron-withdrawing or π-extended substituents on carbazole ligands reduces excited-state M─N π-interactions, thereby improving kTADF, but may impair emitter stability and device operational lifetime.
PMID:
42371660
Bibliographic data and abstract were imported from PubMed on 29 Jun 2026.
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