Substituent engineering of the diboron molecular architecture for a nondoped and ultrathin emitting layer. Issue 44 (3rd November 2022)

• Record Type: Journal Article
• Authors: Wu, Tien-Lin; Lei, Jian; Hsieh, Chia-Min; Chen, Yi-Kuan; Huang, Pei-Yun; Lai, Po-Ting; Chou, Tsu-Yu; Lin, Wei-Chen; Chen, Wei; Yu, Chi-Hua; Hsu, Liang-Yan; Lin, Hao-Wu; Cheng, Chien-Hong
• Is Part Of: Chemical science. Volume 13:Issue 44(2022)
• Page Start: 12996
• Page End: 13005
• Publication Date: 2022-11-03
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2sc04725j
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : A strategy of substituent engineering of DBA-based molecules is investigated via experimental and theoretical methods. A 1 nm-thick emitting layer OLED has been developed. Abstract : Owing to the high technology maturity of thermally activated delayed fluorescence (TADF) emitter design with a specific molecular shape, extremely high-performance organic light-emitting diodes (OLEDs) have recently been achieved via various doping techniques. Recently, undoped OLEDs have drawn immense attention because of their manufacturing cost reduction and procedure simplification. However, capable materials as host emitters are rare and precious because general fluorophores in high-concentration states suffer from serious aggregation-caused quenching (ACQ) and undergo exciton quenching. In this work, a series of diboron materials, CzDBA, iCzDBA, and t BuCzDBA, is introduced to realize the effect of steric hindrance and the molecular aspect ratio via experimental and theoretical studies. We computed transition electric dipole moment (TEDM) and molecular dynamics (MD) simulations as a proof-of-concept model to investigate the molecular stacking in neat films. It is worth noting that the pure t BuCzDBA film with a high horizontal ratio of 92% is employed to achieve a nondoped OLED with an excellent external quantum efficiency of 26.9%. In addition, we demonstrated the first ultrathin emitting layer (1 nm) TADF device, which exhibited outstanding power efficiency. This molecular design and high-performance devices show the potential of power-saving and economical fabrication for advanced OLEDs.