Design and synthesis of yellow- to red-emitting gold() complexes containing isomeric thienopyridine and thienoquinoline moieties and their applications in operationally stable organic light-emitting devices

• Published in: Materials horizons 2022-01, Vol.9 (1), p.281-293
• Main Authors: Li, Lok-Kwan, Au-Yeung, Cathay Chai, Tang, Man-Chung, Lai, Shiu-Lun, Cheung, Wai-Lung, Ng, Maggie, Chan, Mei-Yee, Yam, Vivian Wing-Wah
• Format: Article
• Language: English
• Subjects: Conjugation; Devices; Electroluminescence; Emitters; Gold; Organic light emitting diodes; Photoluminescence; Pyridines; Thin films
• ISSN: 2051-6347; 2051-6355
• DOI: 10.1039/d1mh00821h

A new class of yellow- to red-emitting carbazolylgold( iii ) complexes containing isomeric thienopyridine or thienoquinoline moieties in the cyclometalating ligand has been designed and synthesized, which showed high photoluminescence quantum yields of over 80% in solid-state thin films. The isomeric effect and extended π-conjugation of the N -heterocycles have been found to remarkably perturb the photophysical, electrochemical and electroluminescence properties of the gold( iii ) complexes. In particular, the operational lifetimes of organic light-emitting devices based on that incorporated with thieno[2,3- c ]pyridine are almost three orders of magnitude longer than that incorporated with thieno[3,2- c ]pyridine. This has led to long device operational stability with a LT 70 value of up to 63 200 h at a luminance of 100 cd m −2 and a long half-lifetime of 206 800 h, as well as maximum external quantum efficiencies of up to 8.6% and 14.5% in the solution-processed and vacuum-deposited devices, respectively. This work provides insights into the development of robust and highly luminescent gold( iii ) complexes and the identification of stable molecular motifs for designing efficient emitters. A new class of yellow- to red-emitting carbazolylgold( iii ) complexes containing isomeric thienopyridine and thienoquinoline moieties in the cyclometalating ligand has been designed to realize high performance OLEDs with long operational lifetime.