title: Efficient quantum dot light-emitting diodes by controlling the carrier accumulation and exciton formation.
abstract: The performances and spectroscopic properties of CdSe/ZnS quantum dot light-emitting diodes (QD-LEDs) with inserting a thickness-varied 1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi) layer between the QD emission layer and 4,4-N,N-dicarbazole-biphenyl (CBP) hole transport layer (HTL) are studied. The significant enhancement in device peak efficiency is demonstrated for the device with a 3.5 nm TPBi interlayer. The photoluminescence lifetimes of excitons formed within QDs in different devices are also measured to understand the influence of electric field on the QD emission dynamics process and device efficiency. All the excitons on QDs at different devices have nearly the same lifetime even though at different bias. The improvement of device performance is attributed to the separation of charge carrier accumulation interface from the exciton formation zone, which suppresses exciton quenching caused by accumulated carriers.
authors.affiliation: State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences , Changchun 130033, China.
authors.forename: Wenyu
authors.initials: W
authors.lastname: Ji
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
authors.forename: Qinghui
authors.initials: Q
authors.lastname: Zeng
authors.forename: Songnan
authors.initials: S
authors.lastname: Qu
authors.forename: Ligong
authors.initials: L
authors.lastname: Zhang
authors.forename: Pengtao
authors.initials: P
authors.lastname: Jing
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Jialong
authors.initials: J
authors.lastname: Zhao