title: Highly Luminescent WS2Quantum Dots/ZnO Heterojunctions for Light Emitting Devices.
abstract: Sonication induced vertical fragmentation of two-dimensional (2D) WS2nanosheets into highly luminescent, monodispered, zero-dimensional (0D) quantum dots (QDs) is reported. The formation of 0D structures from 2D sheets and their surface/microstructure characterization are revealed from their microscopic and spectroscopic investigations. Size dependent optical properties of WS2nanostructures have been explored by UV-vis absorption and photoluminescence spectroscopy. Interestingly, it is observed that, below a critical dimension (∼2 nm), comparable to the Bohr exciton radius, the tiny nanocrystals exhibit strong emission. Finally, the electroluminescence characteristics are demonstrated for the first time, by forming a heterojunction of stabilizer free WS2QDs and ZnO thin films. The signature of white light emission in the light emitting device is attributed to the adequate intermixing of emission characteristics of WS2QDs and ZnO. The observation of white electroluminescence may pave the way to fabricate prototype futuristic efficient light emitting devices.
authors.affiliation: School of Nanoscience and Technology, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
authors.forename: Arup
authors.initials: A
authors.lastname: Ghorai
authors.affiliation: Department of Physics, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
authors.forename: Sayan
authors.initials: S
authors.lastname: Bayan
authors.affiliation: Department of Physics, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
authors.forename: Narendar
authors.initials: N
authors.lastname: Gogurla
authors.affiliation: School of Nanoscience and Technology, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
authors.forename: Anupam
authors.identifier: http://orcid.org/0000-0003-0498-6017
authors.initials: A
authors.lastname: Midya
authors.affiliation: Department of Physics, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
authors.forename: Samit K
authors.initials: SK
authors.lastname: Ray
keywords: electroluminescence; nanocrystals; quantum confinement; quantum dots; transition metal dichalcogenides (TMDC); tungsten sulfide WS2