title: Improved electroluminescence of quantum dot light-emitting diodes enabled by a partial ligand exchange with benzenethiol.
abstract: In this study, benzenethiol ligands were applied to the surface of CdSe@ZnS core@shell quantum dots (QDs) and their effect on the performance of quantum dot light-emitting diodes (QD-LEDs) was investigated. Conventional long-chained oleic acid (OA) and trioctylphosphine (TOP) capping ligands were partially replaced by short-chained benzenethiol ligands in order to increase the stability of QDs during purification and also improve the electroluminescence performance of QD-LEDs. The quantum yield of the QD solution was increased from 41% to 84% by the benzenethiol ligand exchange. The mobility of the QD films with benzenethiol ligands approximately doubled to 2.42 × 10(-5) cm(2) V(-1) s(-1) from 1.19 × 10(-5) cm(2) V(-1) s(-1) compared to the device consisting of OA/TOP-capped QDs, and an approximately 1.8-fold improvement was achieved over QD-LEDs fabricated with bezenethiol ligand-exchanged QDs with respect to the maximum luminance and current efficiency. The turn-on voltage decreased by about -0.6 V through shifting the energy level of the QDs with benzenethiol ligands compared to conventional OA and TOP ligands.
authors.affiliation: Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 440-746, Korea.
authors.forename: Daekyoung
authors.initials: D
authors.lastname: Kim
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon 440-746, Korea.
authors.forename: Yan
authors.initials: Y
authors.lastname: Fu
authors.affiliation: School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon 440-746, Korea.
authors.forename: Jungwoo
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, Hongik University, Seoul 121-791, Korea.
authors.forename: Ki-Heon
authors.initials: KH
authors.lastname: Lee
authors.affiliation: School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon 440-746, Korea.
authors.forename: Hyoungsub
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Materials Science and Engineering, Hongik University, Seoul 121-791, Korea.
authors.forename: Heesun
authors.initials: H
authors.lastname: Yang
authors.affiliation: Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 440-746, Korea.|School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon 440-746, Korea.
authors.forename: Heeyeop
authors.initials: H
authors.lastname: Chae