Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

The linear photochemical response of materials depends on two critical parameters: the size of the optical band gap determines the onset of optical excitation, whereas the absolute energetic positions of the band edges define the reductive or oxidative character of photo-generated electrons and hole...

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Main Authors: Dominik Voigt, Larry Sarpong, Michael Bredol
Format: Article
Language:English
Published: MDPI AG 2020-09-01
Series:Materials
Subjects:
Online Access:https://www.mdpi.com/1996-1944/13/18/4162
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author Dominik Voigt
Larry Sarpong
Michael Bredol
author_facet Dominik Voigt
Larry Sarpong
Michael Bredol
author_sort Dominik Voigt
collection DOAJ
description The linear photochemical response of materials depends on two critical parameters: the size of the optical band gap determines the onset of optical excitation, whereas the absolute energetic positions of the band edges define the reductive or oxidative character of photo-generated electrons and holes. Tuning these characteristics is necessary for many potential applications and can be achieved through changes in the bulk composition or particle size, adjustment of the surface chemistry or the application of electrostatic fields. In this contribution the influence of surface chemistry and fields is investigated systematically with the help of standard DFT calculations for a typical case, namely composites prepared from ZnS quantum dots and functionalized carbon nanotubes. After comparing results with existing qualitative and quantitative experimental data, it is shown conclusively, that the details of the surface chemistry (especially defects) in combination with electrostatic fields have the largest influence. In conclusion, the development of novel or improved photoresponsive materials therefore will have to integrate a careful analysis of the interplay between surface chemistry, surface charges and interaction with the material environment or substrate.
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spelling doaj.art-60c23130d1c044eb98671ea7261917452023-11-20T14:18:21ZengMDPI AGMaterials1996-19442020-09-011318416210.3390/ma13184162Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/CarbonDominik Voigt0Larry Sarpong1Michael Bredol2Department of Chemical Engineering, FH Münster University of Applied Sciences, 48565 Steinfurt, GermanyDepartment of Chemical Engineering, FH Münster University of Applied Sciences, 48565 Steinfurt, GermanyDepartment of Chemical Engineering, FH Münster University of Applied Sciences, 48565 Steinfurt, GermanyThe linear photochemical response of materials depends on two critical parameters: the size of the optical band gap determines the onset of optical excitation, whereas the absolute energetic positions of the band edges define the reductive or oxidative character of photo-generated electrons and holes. Tuning these characteristics is necessary for many potential applications and can be achieved through changes in the bulk composition or particle size, adjustment of the surface chemistry or the application of electrostatic fields. In this contribution the influence of surface chemistry and fields is investigated systematically with the help of standard DFT calculations for a typical case, namely composites prepared from ZnS quantum dots and functionalized carbon nanotubes. After comparing results with existing qualitative and quantitative experimental data, it is shown conclusively, that the details of the surface chemistry (especially defects) in combination with electrostatic fields have the largest influence. In conclusion, the development of novel or improved photoresponsive materials therefore will have to integrate a careful analysis of the interplay between surface chemistry, surface charges and interaction with the material environment or substrate.https://www.mdpi.com/1996-1944/13/18/4162optical band gapband edgequantum dotnanocompositeDFT
spellingShingle Dominik Voigt
Larry Sarpong
Michael Bredol
Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon
Materials
optical band gap
band edge
quantum dot
nanocomposite
DFT
title Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon
title_full Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon
title_fullStr Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon
title_full_unstemmed Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon
title_short Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon
title_sort tuning the optical band gap of semiconductor nanocomposites a case study with zns carbon
topic optical band gap
band edge
quantum dot
nanocomposite
DFT
url https://www.mdpi.com/1996-1944/13/18/4162
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AT larrysarpong tuningtheopticalbandgapofsemiconductornanocompositesacasestudywithznscarbon
AT michaelbredol tuningtheopticalbandgapofsemiconductornanocompositesacasestudywithznscarbon