title: Ideal Molecular Design of Blue Thermally Activated Delayed Fluorescent Emitter for High Efficiency, Small Singlet-Triplet Energy Splitting, Low Efficiency Roll-Off, and Long Lifetime.
abstract: Highly efficient thermally activated delayed fluorescent (TADF) emitters, 5-(2-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5H-benzofuro[3,2-c]carbazole (oBFCzTrz), 5-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5H-benzofuro[3,2-c]carbazole (mBFCzTrz), and 5-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5H-benzofuro[3,2-c]carbazole (pBFCzTrz), were synthesized to study the effects of ortho-, meta-, and para- linkages between donor and acceptor moieties. oBFCzTrz having ortho- linked donor and acceptor moieties showed smaller singlet-triplet energy gap, shorter excited state lifetime, and higher photoluminescence quantum yield than mBFCzTrz and pBFCzTrz which are interconnected by meta- and para- positions. The TADF device using oBFCzTrz as a blue emitter exhibited high external quantum efficiency over 20%, little efficiency roll-off, and long device lifetime.
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi 440-746, Korea.
authors.forename: Dong Ryun
authors.initials: DR
authors.lastname: Lee
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi 440-746, Korea.
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Choi
authors.affiliation: Department of Polymer Science and Engineering, Dankook University , 126 Jukjeon-dong, Suji-gu, Yongin, Gyeonggi 448-701, Korea.
authors.forename: Chil Won
authors.initials: CW
authors.lastname: Lee
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University , 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi 440-746, Korea.
authors.forename: Jun Yeob
authors.initials: JY
authors.lastname: Lee
keywords: charge transfer; delayed fluorescence; ortho- linkage; singlet energy; triplet energy