Journal article
Thiocyanate-Capped Nanocrystal Colloids: Vibrational Reporter of Surface Chemistry and Solution-Based Route to Enhanced Coupling in Nanocrystal Solids
Journal of the American Chemical Society, v 133(39), pp 15753-15761
05 Oct 2011
PMID: 21848336
Abstract
Ammonium thiocyanate (NH4SCN) is introduced to exchange the long, insulating ligands used in colloidal nanocrystal (NC) synthesis. The short, air-stable, environmentally benign thiocyanate ligand electrostatically stabilizes a variety of semiconductor and metallic NCs in polar solvents, allowing solution-based deposition of NCs into thin-film NC solids. NH4SCN is also effective in replacing ligands on NCs after their assembly into the solid state. The spectroscopic properties of this ligand provide unprecedented insight into the chemical and electronic nature of the surface of the NCs. Spectra indicate that the thiocyanate binds to metal sites on the NC surface and is sensitive to atom type and NC surface charge. The short, thiocyanate ligand gives rise to significantly enhanced electronic coupling between NCs as evidenced by large bathochromic shifts in the absorption spectra of CdSe and CdTe NC thin films and by conductivities as high as (2 +/- 0.7) x 10(3) Omega(-1) cm(-1) for Au NC thin films deposited from solution. NH4SCN treatment of PbTe NC films increases the conductivity by 10(13), allowing the first Hall measurements of nonsintered NC solids, with Hall effect mobilities of 2.8 +/- 0.7 cm(2)/(V.s). Thiocyanate-capped CdSe NC thin films form photodetectors exhibiting sensitive photoconductivity of 10(-5) Omega(-1) cm(-1) under 30 mW/cm(2) of 488 nm illumination with I-photo/I-dark > 10(3) and form n-channel thin-film transistors with electron mobilities of 1.5 +/- 0.7 cm(2)/(V.s), a current modulation of >10(6), and a subthreshold swing of 0.73 V/decade.
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Details
- Title
- Thiocyanate-Capped Nanocrystal Colloids: Vibrational Reporter of Surface Chemistry and Solution-Based Route to Enhanced Coupling in Nanocrystal Solids
- Creators
- Aaron T. Fafarman - University of PennsylvaniaWeon-kyu Koh - University of PennsylvaniaBenjamin T. Diroll - University of PennsylvaniaDavid K. Kim - University of PennsylvaniaDong-Kyun Ko - University of PennsylvaniaSoong Ju Oh - University of PennsylvaniaXingchen Ye - University of PennsylvaniaVicky Doan-Nguyen - University of PennsylvaniaMichael R. Crump - University of PennsylvaniaDanielle C. Reifsnyder - University of PennsylvaniaChristopher B. Murray - University of PennsylvaniaCherie R. Kagan - University of Pennsylvania
- Publication Details
- Journal of the American Chemical Society, v 133(39), pp 15753-15761
- Publisher
- American Chemical Society; Washington, DC
- Number of pages
- 9
- Grant note
- CBET-0854226 / NSF-CBET; National Science Foundation (NSF) 0935165 / Direct For Mathematical & Physical Scien; Division Of Mathematical Sciences; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS) 1120901 / Direct For Mathematical & Physical Scien; Division Of Materials Research; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS) DGE-0221664 / NSF-IGERT; National Science Foundation (NSF) DE-AR0000123 / Department of Energy, DOE Office of ARPA-E; United States Department of Energy (DOE) DMS-0935165 / NSF; National Science Foundation (NSF) ONR-N00014-10-1-0942 / Office of Naval Research MURI; MURI; Office of Naval Research DE-SC0002158 / U.S. Department of Energy Office of Basic Energy Sciences, Division of Materials Science and Engineering; United States Department of Energy (DOE) DMR-0520020 / NSF MRSEC; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemical and Biological Engineering
- Web of Science ID
- WOS:000295911500080
- Scopus ID
- 2-s2.0-80053319254
- Other Identifier
- 991020834416904721
InCites Highlights
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- Web of Science research areas
- Chemistry, Multidisciplinary