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Title: Direct conversion of hydride- to siloxane-terminated silicon quantum dots

Here, peripheral surface functionalization of hydride-terminated silicon quantum dots (SiQD) is necessary in order to minimize their oxidation/aggregation and allow for solution processability. Historically thermal hydrosilylation addition of alkenes and alkynes across the Si-H surface to form Si-C bonds has been the primary method to achieve this. Here we demonstrate a mild alternative approach to functionalize hydride-terminated SiQDs using bulky silanols in the presence of free-radical initiators to form stable siloxane (~Si-O-SiR 3) surfaces with hydrogen gas as a byproduct. This offers an alternative to existing methods of forming siloxane surfaces that require corrosive Si-Cl based chemistry with HCl byproducts. A 52 nm blue shift in the photoluminescent spectra of siloxane versus alkyl-functionalized SiQDs is observed that we explain using computational theory. Model compound synthesis of silane and silsesquioxane analogues is used to optimize surface chemistry and elucidate reaction mechanisms. Thorough characterization on the extent of siloxane surface coverage is provided using FTIR and XPS. As a result, TEM is used to demonstrate SiQD size and integrity after surface chemistry and product isolation.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [4]
  1. Colorado School of Mines, Golden, CO (United States)
  2. Colorado School of Mines, Golden, CO (United States); Emory Univ., Atlanta, GA (United States)
  3. Colorado School of Mines, Golden, CO (United States); Brown Univ., Providence, RI (United States)
  4. Colorado School of Mines, Golden, CO (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5900-67533
Journal ID: ISSN 1932-7447
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 120; Journal Issue: 45; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; hydride-terminated silicon quantum dots; SiQD; silanols; siloxane
OSTI Identifier:
1335217

Anderson, Ryan T., Zang, Xiaoning, Fernando, Roshan, Dzara, Michael J., Ngo, Chilan, Sharps, Meredith, Pinals, Rebecca, Pylypenko, Svitlana, Lusk, Mark T., and Sellinger, Alan. Direct conversion of hydride- to siloxane-terminated silicon quantum dots. United States: N. p., Web. doi:10.1021/acs.jpcc.6b07930.
Anderson, Ryan T., Zang, Xiaoning, Fernando, Roshan, Dzara, Michael J., Ngo, Chilan, Sharps, Meredith, Pinals, Rebecca, Pylypenko, Svitlana, Lusk, Mark T., & Sellinger, Alan. Direct conversion of hydride- to siloxane-terminated silicon quantum dots. United States. doi:10.1021/acs.jpcc.6b07930.
Anderson, Ryan T., Zang, Xiaoning, Fernando, Roshan, Dzara, Michael J., Ngo, Chilan, Sharps, Meredith, Pinals, Rebecca, Pylypenko, Svitlana, Lusk, Mark T., and Sellinger, Alan. 2016. "Direct conversion of hydride- to siloxane-terminated silicon quantum dots". United States. doi:10.1021/acs.jpcc.6b07930. https://www.osti.gov/servlets/purl/1335217.
@article{osti_1335217,
title = {Direct conversion of hydride- to siloxane-terminated silicon quantum dots},
author = {Anderson, Ryan T. and Zang, Xiaoning and Fernando, Roshan and Dzara, Michael J. and Ngo, Chilan and Sharps, Meredith and Pinals, Rebecca and Pylypenko, Svitlana and Lusk, Mark T. and Sellinger, Alan},
abstractNote = {Here, peripheral surface functionalization of hydride-terminated silicon quantum dots (SiQD) is necessary in order to minimize their oxidation/aggregation and allow for solution processability. Historically thermal hydrosilylation addition of alkenes and alkynes across the Si-H surface to form Si-C bonds has been the primary method to achieve this. Here we demonstrate a mild alternative approach to functionalize hydride-terminated SiQDs using bulky silanols in the presence of free-radical initiators to form stable siloxane (~Si-O-SiR3) surfaces with hydrogen gas as a byproduct. This offers an alternative to existing methods of forming siloxane surfaces that require corrosive Si-Cl based chemistry with HCl byproducts. A 52 nm blue shift in the photoluminescent spectra of siloxane versus alkyl-functionalized SiQDs is observed that we explain using computational theory. Model compound synthesis of silane and silsesquioxane analogues is used to optimize surface chemistry and elucidate reaction mechanisms. Thorough characterization on the extent of siloxane surface coverage is provided using FTIR and XPS. As a result, TEM is used to demonstrate SiQD size and integrity after surface chemistry and product isolation.},
doi = {10.1021/acs.jpcc.6b07930},
journal = {Journal of Physical Chemistry. C},
number = 45,
volume = 120,
place = {United States},
year = {2016},
month = {10}
}