title: Pyridyl Pyrrolide Boron Complexes: The Facile Generation of Thermally Activated Delayed Fluorescence and Preparation of Organic Light-Emitting Diodes.
abstract: The electron positive boron atom usually does not contribute to the frontier orbitals for several lower-lying electronic transitions, and thus is ideal to serve as a hub for the spiro linker of light-emitting molecules, such that the electron donor (HOMO) and acceptor (LUMO) moieties can be spatially separated with orthogonal orientation. On this basis, we prepared a series of novel boron complexes bearing electron deficient pyridyl pyrrolide and electron donating phenylcarbazolyl fragments or triphenylamine. The new boron complexes show strong solvent-polarity dependent charge-transfer emission accompanied by a small, non-negligible normal emission. The slim orbital overlap between HOMO and LUMO and hence the lack of electron correlation lead to a significant reduction of the energy gap between the lowest lying singlet and triplet excited states (ΔET-S ) and thereby the generation of thermally activated delay fluorescence (TADF).
authors.affiliation: Graduate Institute of Electronics Engineering and Department of Electrical Engineering, National Taiwan University, Taipei, 10617, Taiwan.
authors.forename: Yi-Jiun
authors.initials: YJ
authors.lastname: Shiu
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan.
authors.forename: Yung-Chen
authors.initials: YC
authors.lastname: Cheng
authors.affiliation: Graduate Institute of Electronics Engineering and Department of Electrical Engineering, National Taiwan University, Taipei, 10617, Taiwan.
authors.forename: Wei-Lung
authors.initials: WL
authors.lastname: Tsai
authors.affiliation: Graduate Institute of Electronics Engineering and Department of Electrical Engineering, National Taiwan University, Taipei, 10617, Taiwan. wucc@ntu.edu.tw.
authors.forename: Chung-Chih
authors.initials: CC
authors.lastname: Wu
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan.
authors.forename: Chun-Tien
authors.initials: CT
authors.lastname: Chao
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan.
authors.forename: Chin-Wei
authors.initials: CW
authors.lastname: Lu
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan. ychi@mx.nthu.edu.tw.
authors.forename: Yun
authors.initials: Y
authors.lastname: Chi
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Chen
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan.
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Liu
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan. chop@ntu.edu.tw.
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
keywords: OLEDs; boron; photoluminescence; thermally activated delay fluorescence