Phosphorescent Carbene‐Gold‐Arylacetylide Materials as Emitters for Near UV‐OLEDs

• Published in: Advanced materials (Weinheim) Vol. 36; no. 5; pp. e2306249 - n/a
• Main Authors: Brannan, Alexander C., Cho, Hwan‐Hee, Reponen, Antti‐Pekka M., Linnolahti, Mikko, Bochmann, Manfred, Greenham, Neil C., Romanov, Alexander S.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.02.2024
• Subjects: carbene; Carbenes; Charge transfer; Density functional theory; electroluminescence; Emitters; Energy gap; Gold; Luminescence; Organic light emitting diodes; Phosphorescence; Physical vapor deposition; Service life assessment; UV‐OLED; gold; phosphorescence; UV-OLED; carbene; electroluminescence
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202306249

A series of carbene‐gold‐acetylide complexes [(BiCAAC)AuCC]nC6H5−n (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 (S1) and triplet excited (T1) 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 LT50 up to 20 min at practical brightness of 10 nits, indicating a highly promising class of materials to develop stable UV‐OLEDs. Carbene‐gold‐acetylide (CMAc) complexes are bright deep‐blue and green phosphorescent emitters with quantum yields up to 43% which also show UV prompt‐fluorescence. Organic light‐emitting diodes based on CMAc emitters show near‐UV electroluminescence with a device efficiency of 1% and a device lifetime LT50 up to 20 min at practical brightness.