Phosphorescent Carbene-Gold-Arylacetylide Materials as Emitters for Near UV-OLEDs.
basic_science · Level V
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- Record sourced from PubMed, PMID 37656901.
- Also identified by DOI 10.1002/adma.202306249.
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Abstract
A series of carbene-gold-acetylide complexes [(BiCAAC)AuCC]<sub>n</sub> C<sub>6</sub> H<sub>5-</sub> <sub>n</sub> (n = 1, Au1; n = 2, Au2; n = 3, Au3; BiCAAC = bicyclic(alkyl)(amino)carbene) have been synthesized in high yields. Compounds Au1-Au3 exhibit deep-blue to blue-green phosphorescence with good quantum yields up to 43% in all media. An increase of the (BiCAAC)Au moieties in gold complexes Au1-Au3 increases the extinction coefficients in the UV-vis spectra and stronger oscillator strength coefficients supported by theoretical calculations. The luminescence radiative rates decrease with an increase of the (BiCAAC)Au moieties. The time-dependent density functional theory study supports a charge-transfer nature of the phosphorescence due to the large (0.5-0.6 eV) energy gap between singlet excited (S<sub>1</sub> ) and triplet excited (T<sub>1</sub> ) states. Transient luminescence study reveals the presence of both nonstructured UV prompt-fluorescence and vibronically resolved long-lived phosphorescence 428 nm. Organic light-emitting diodes (OLED) are fabricated by physical vapor deposition with 2,8-bis(diphenylphosphoryl)dibenzo[b,d]furan (PPF) as a host material with complex Au1. The near-UV electroluminescence is observed at 405 nm with device efficiency of 1% while demonstrating OLED device lifetime LT<sub>50</sub> up to 20 min at practical brightness of 10 nits, indicating a highly promising class of materials to develop stable UV-OLEDs.