title: Photoresponse of an Organic Semiconductor/Two-Dimensional Transition Metal Dichalcogenide Heterojunction.
abstract: We study the optoelectronic properties of a type-II heterojunction (HJ) comprising a monolayer of the transition metal dichalcogenide (TMDC), WS2, and a thin film of the organic semiconductor, 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA). Both theoretical and experimental investigations of the HJ indicate that Frenkel states in the organic layer and two-dimensional Wannier-Mott states in the TMDC dissociate to form hybrid charge transfer excitons at the interface that subsequently dissociate into free charges that are collected at opposing electrodes. A photodiode employing the HJ achieves a peak external quantum efficiency of 1.8 ± 0.2% at a wavelength of 430 ± 10 nm, corresponding to an internal quantum efficiency (IQE) as high as 11 ± 1% in these ultrathin devices. The photoluminescence spectra of PTCDA and PTCDA/WS2thin films show that excitons in the WS2have a quenching rate that is approximately seven times higher than in PTCDA. This difference leads to strong wavelength dependence in IQE.
authors.forename: Xiao
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Physics, City College of New York , New York, New York 10031, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Gu
authors.forename: Kan
authors.initials: K
authors.lastname: Ding
authors.forename: Dejiu
authors.initials: D
authors.lastname: Fan
authors.forename: Xiaoer
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Materials Science & Technology, National Tsing Hua University , Hsinchu City, Taiwan.
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Tseng
authors.affiliation: Department of Materials Science & Technology, National Tsing Hua University , Hsinchu City, Taiwan.
authors.forename: Yi-Hsien
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Physics, City College of New York , New York, New York 10031, United States.
authors.forename: Vinod
authors.initials: V
authors.lastname: Menon
authors.forename: Stephen R
authors.identifier: 0000-0003-0131-1903
authors.initials: SR
authors.lastname: Forrest
keywords: Transition metal dichalcogenide; hybrid charge transfer excitons; organic−inorganic heterojunction; photoluminescence; quantum efficiency