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This content will become publicly available on May 17, 2019

Title: Distinct Optoelectronic Signatures for Charge Transfer and Energy Transfer in Quantum Dot-MoS 2 Hybrid Photodetectors Revealed by Photocurrent Imaging Microscopy

Atomically thin transition metal dichalcogenides (TMDCs) have intriguing nanoscale properties like high charge mobility, photosensitivity, layer-thickness-dependent bandgap, and mechanical flexibility, which are all appealing for the development of next generation optoelectronic, catalytic, and sensory devices. Their atomically thin thickness, however, renders TMDCs poor absorptivity. For this study, bilayer MoS 2 is combined with core-only CdSe QDs and core/shell CdSe/ZnS QDs to obtain hybrids with increased light harvesting and exhibiting interfacial charge transfer (CT) and nonradiative energy transfer (NET), respectively. Field-effect transistors based on these hybrids and their responses to varying laser power and applied gate voltage are investigated with scanning photocurrent microscopy (SPCM) in view of their potential utilization in light harvesting and photodetector applications. CdSe–MoS 2 hybrids are found to exhibit encouraging properties for photodetectors, like high responsivity and fast on/off response under low light exposure while CdSe/ZnS–MoS 2 hybrids show enhanced charge carrier generation with increased light exposure, thus suitable for photovoltaics. While distinguishing optically between CT and NET in QD–TMDCs is nontrivial, it is found that they can be differentiated by SPCM as these two processes exhibit distinctive light-intensity dependencies: CT causes a photogating effect, decreasing the photocurrent response with increasing light power while NET increases themore » photocurrent response with increasing light power, opposite to CT case.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [1] ; ORCiD logo [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN); Stony Brook Univ., NY (United States). Dept. of Materials Science and Chemical Engineering
  3. Stony Brook Univ., NY (United States). Dept. of Materials Science and Chemical Engineering; Columbia Univ., New York, NY (United States). Dept. of Physics
Publication Date:
Report Number(s):
BNL-205746-2018-JAAM
Journal ID: ISSN 1616-301X
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Advanced Functional Materials
Additional Journal Information:
Journal Name: Advanced Functional Materials; Journal ID: ISSN 1616-301X
Publisher:
Wiley
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; transition metal dichalcogenides; TMDCs; colloidal quantum dots; light harvesting; excitonic nanomaterials; photocurrent imaging; charge transfer; energy transfer
OSTI Identifier:
1440894
Alternate Identifier(s):
OSTI ID: 1437667