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Title: Ligand-induced dependence of charge transfer in nanotube–quantum dot heterostructures

As a model system to probe ligand-dependent charge transfer in complex composite heterostructures, we fabricated double-walled carbon nanotube (DWNT) – CdSe quantum dot (QD) composites. Whereas the average diameter of the QDs probed was kept fixed at ~4.1 nm and the nanotubes analyzed were similarly oxidatively processed, by contrast, the ligands used to mediate the covalent attachment between the QDs and DWNTs were systematically varied to include p-phenylenediamine (PPD), 2-aminoethanethiol (AET), and 4-aminothiophenol (ATP). Herein, we have put forth a unique compilation of complementary data from experiment and theory, including results from transmission electron microscopy (TEM), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, Raman spectroscopy, electrical transport measurements, and theoretical modeling studies, in order to fundamentally assess the nature of the charge transfer between CdSe QDs and DWNTs, as a function of the structure of various, intervening bridging ligand molecules. Specifically, we correlated evidence of charge transfer as manifested by changes and shifts associated with NEXAFS intensities, Raman peak positions, and threshold voltages both before and after CdSe QD deposition onto the underlying DWNT surface. Importantly, for the first time ever in these types of nanoscale composite systems, we have sought to use theoretical modeling to justify and account formore » our experimental results. Finally, our overall data suggest that (i) QD coverage density on the DWNTs varies, based upon the different ligand pendant groups used and that (ii) the presence of a π-conjugated carbon framework within the ligands themselves and the electron affinity of the pendant groups collectively play important roles in the resulting charge transfer from QDs to the underlying CNTs.« less
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [4] ;  [5] ;  [1] ;  [6] ;  [6] ;  [5] ;  [4] ;  [7] ;  [8]
  1. Stony Brook Univ., NY (United States). Dept. of Chemistry
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Sciences Division
  3. State Univ. of New York (SUNY) at Stony Brook, Stony Brook, NY (United States). Inst. of Advanced Computational Science
  4. Purdue Univ., West Lafayette, IN (United States). Birck Nanotechnology Center, Dept. of Electrical and Computer Engineering
  5. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Material Measurement Lab.
  6. State Univ. of New York (SUNY) at Stony Brook, Stony Brook, NY (United States). School of Marine and Atmospheric Sciences
  7. State Univ. of New York (SUNY) at Stony Brook, Stony Brook, NY (United States). Inst. of Advanced Computational Science; Brookhaven National Lab. (BNL), Upton, NY (United States). Computational Science Center
  8. Stony Brook Univ., NY (United States). Dept. of Chemistry; Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Sciences Division
Publication Date:
OSTI Identifier:
1303000
Report Number(s):
BNL--112413-2016-JA
Journal ID: ISSN 2040-3364; NANOHL; R&D Project: PM037; KC0201030
Grant/Contract Number:
SC00112704; ACI-121664; OCE-1336724
Type:
Accepted Manuscript
Journal Name:
Nanoscale
Additional Journal Information:
Journal Name: Nanoscale; Journal ID: ISSN 2040-3364
Publisher:
Royal Society of Chemistry
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:
77 NANOSCIENCE AND NANOTECHNOLOGY; 36 MATERIALS SCIENCE NEXAFS; theoretical modeling; charge transfer; CdSe QDs; DWNTs; ligands