kth.sePublikationer
Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Fabrication and Photoelectrochemical Applications of II-VI Semiconductor Nanomaterials
KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
2012 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

In this work we investigated fabrication of semiconductor nanomaterials and evaluated their potential for photo-chemical and photovoltaic applications. We investigated different II-VI semiconductor nanomaterial systems; (i) ZnO oriented nanowire arrays non-epitaxially grown from a substrate; and (ii) colloidal CdE (E=Te,Se,S) quantum structures synthesized by solution-based thermal decomposition of organo-metallic precursors.

We have studied the synthesis of vertically aligned ZnO nanowire arrays (NWA), by a wet chemical process on various substrates. We have extended this method wherein nanofibers of poly-L-lactide act as a substrate for the radially oriented growth of ZnO nanowires. By combining the large surface area and the flexibility of the PLLA-ZnO hierarchical nanostructure we have shown the proof-of-principle demonstration of a ‘continuous-flow’ water treatment system to decompose known organic pollutants in water, as well as render common waterborne bacteria non-viable.

We have studied synthesis of colloidal quantum dots (QD), and show size, morphology and composition tailored nanocrystals for CdE (E=S, Se, Te) compositions. We have studied the influence of crystal growth habits of the nanocrtsyals on the final morphology. Furthermore we have synthesized core-shell, CdSe-CdS QDs with spherical and tetrahedral morphologies by varying the reaction conditions. We show that these core-shell quantum dots show quasi-type II characteristics, and demonstrate with I-V measurements, the spatial localization of the charge carriers in these hetero-nanocrystals. For this purpose, we developed hybrid materials consisting of the core-shell quantum dots with electron acceptors (ZnO nanowires) and hole acceptors (polymeric P3HT nanofibers).

In addition we have also compared the synthesis reaction when carried out with conventional heating and microwave-mediated heating. We find that the reaction is enhanced, and the yield is qualitatively better when using microwave induced heating.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2012. , s. viii, 55
Serie
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2012:09
Nyckelord [en]
ZnO, nanowire arrays, photocatalysis, CdTe, CdSe, CdS, nanotetrapods, nanotetrahedrons, photoconduction, nano-gap electrodes, Type-II QDs, P3HT nanofibers, microwave synthesis.
Nationell ämneskategori
Nanoteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-95410ISBN: 978-91-7501-382-4 (tryckt)OAI: oai:DiVA.org:kth-95410DiVA, id: diva2:528172
Disputation
2012-05-31, Sal/Hall C2, KTH-ICT Electrum, Isafjordsgatan-22, Kista, 10:00 (Engelska)
Opponent
Handledare
Anmärkning
QC 20120525Tillgänglig från: 2012-05-25 Skapad: 2012-05-24 Senast uppdaterad: 2022-06-24Bibliografiskt granskad
Delarbeten
1. Zinc oxide nanowires in chemical bath on seeded substrates: Role of hexamine
Öppna denna publikation i ny flik eller fönster >>Zinc oxide nanowires in chemical bath on seeded substrates: Role of hexamine
2006 (Engelska)Ingår i: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 39, nr 1, s. 49-56Artikel i tidskrift (Refereegranskat) Published
Identifikatorer
urn:nbn:se:kth:diva-13234 (URN)10.1007/s10971-006-6969-y (DOI)000239432100006 ()2-s2.0-33746931705 (Scopus ID)
Anmärkning
QC20100614Tillgänglig från: 2010-06-07 Skapad: 2010-06-07 Senast uppdaterad: 2022-06-25Bibliografiskt granskad
2. Radially Oriented ZnO Nanowires on Flexible Poly-L-Lactide Nanofibers for Continuous-Flow Photocatalytic Water Purification
Öppna denna publikation i ny flik eller fönster >>Radially Oriented ZnO Nanowires on Flexible Poly-L-Lactide Nanofibers for Continuous-Flow Photocatalytic Water Purification
Visa övriga...
2010 (Engelska)Ingår i: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 93, nr 11, s. 3740-3744Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Several oxide ceramics, notably ZnO and TiO2 are known to catalyze decomposition of organic molecules in water under ultraviolet (UV) irradiation. Here we describe fabrication of highly flexible ZnO-based hierarchical nanostructure obtained by growing radially oriented ZnO nanowires on poly-L-lactide nanofibers. Utilizing the flexibility and high surface area of polymeric nanofibers as novel substrate for growth of the photochemically active ZnO nanowires we show a proof-of-principle demonstration of a continuous flow water treatment setup. We have monitored photocatalytic decomposition of known organic pollutants, such as methylene blue, monocrotophos, and diphenylamine under illumination with UV light using this highly flexible hierarchical nanostructure.

Nyckelord
ZINC-OXIDE, NANOROD ARRAYS, DEGRADATION, SUSPENSIONS, TIO2, PHOTODEGRADATION, LIGHT
Nationell ämneskategori
Annan materialteknik
Identifikatorer
urn:nbn:se:kth:diva-27677 (URN)10.1111/j.1551-2916.2010.03986.x (DOI)000283987400042 ()2-s2.0-78549235835 (Scopus ID)
Konferens
34th International Conference and Exposition on Advanced Ceramics and Composites Daytona Beach, FL, JAN 26, 2010
Anmärkning
34th International Conference and Exposition on Advanced Ceramics and Composites Daytona Beach, FL, JAN 26, 2010 QC 20101223Tillgänglig från: 2010-12-23 Skapad: 2010-12-20 Senast uppdaterad: 2024-03-15Bibliografiskt granskad
3. Low-temperature synthesis of photoconducting CdTe nanotetrapods
Öppna denna publikation i ny flik eller fönster >>Low-temperature synthesis of photoconducting CdTe nanotetrapods
Visa övriga...
2010 (Engelska)Ingår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 20, nr 6, s. 1208-1214Artikel i tidskrift (Refereegranskat) Published
Nyckelord
SHAPE-CONTROLLED SYNTHESIS, CDSE NANOCRYSTALS, SOLAR-CELLS, NANORODS, GROWTH, TETRAPODS, NANOPARTICLES, MONODISPERSE, COMPOSITES, EVOLUTION
Nationell ämneskategori
Fysikalisk kemi Materialteknik
Identifikatorer
urn:nbn:se:kth:diva-13235 (URN)10.1039/b916208a (DOI)000273961900028 ()2-s2.0-77949558021 (Scopus ID)
Forskningsfinansiär
Knut och Alice Wallenbergs Stiftelse, UAW2004.0224
Anmärkning
QC 20110121Tillgänglig från: 2010-06-07 Skapad: 2010-06-07 Senast uppdaterad: 2024-03-18Bibliografiskt granskad
4. Microwave mediated synthesis of semiconductor quantum dots
Öppna denna publikation i ny flik eller fönster >>Microwave mediated synthesis of semiconductor quantum dots
Visa övriga...
2012 (Engelska)Ingår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, nr 7, s. 1551-1556Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Colloidal quantum dots (QD) have tuneable optoelectronic properties and can be easily handled by simple solution processing techniques, making them very attractive for a wide range of applications. Over the past decade synthesis of morphology controlled high quality (crystalline, monodisperse) colloidal QDs by thermal decomposition of organometallic precursors has matured and is well studied. Recently, synthesis of colloidal QDs by microwave irradiation as heating source is being studied due to the inherently different mechanisms of heat transfer, when compared to solvent convection based heating. Under microwave irradiation, polar precursor molecules directly absorb the microwave energy and heat up more efficiently. Here we report synthesis of colloidal II-VI semiconductor QDs (CdS, CdSe, CdTe) by microwave irradiation and compare it with conventional synthesis based on convection heating. Our findings show that QD synthesis by microwave heating is more efficient and the chalcogenide precursor strongly absorbs the microwave radiation shortening the reaction time and giving a high reaction yield.

Nyckelord
CdSe, Microwave, Quantum dots, Reaction rate
Nationell ämneskategori
Nanoteknik
Identifikatorer
urn:nbn:se:kth:diva-95406 (URN)10.1002/pssc.201100545 (DOI)000306479300007 ()2-s2.0-84864000771 (Scopus ID)
Konferens
16th International Semiconducting and Insulating Materials Conference (SIMC-XVI) Location: Royal Inst Technol (KTH), Stockholm, Sweden Date: JUN 19-23, 2011
Anmärkning
QC 20120810Tillgänglig från: 2012-05-24 Skapad: 2012-05-24 Senast uppdaterad: 2024-03-18Bibliografiskt granskad
5. Synthesis of tetrahedral quasi-type-II CdSe-CdS core-shell quantum dots
Öppna denna publikation i ny flik eller fönster >>Synthesis of tetrahedral quasi-type-II CdSe-CdS core-shell quantum dots
Visa övriga...
2011 (Engelska)Ingår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 22, nr 42, s. 425202-Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Synthesis of colloidal nanocrystals of II-VI semiconductor materials has been refined in recent decades and their size dependent optoelectronic properties have been well established. Here we report a facile synthesis of CdSe-CdS core-shell heterostructures using a two-step hot injection process. Red-shifts in absorption and photoluminescence spectra show that the obtained quantum dots have quasi-type-II alignment of energy levels. The obtained nanocrystals have a heterostructure with a large and highly faceted tetrahedral CdS shell grown epitaxially over a spherical CdSe core. The obtained morphology as well as high resolution electron microscopy confirms that the tetrahedral shell have a zinc blende crystal structure. A phenomenological mechanism for the growth and morphology of the nanocrystals is discussed.

Nationell ämneskategori
Nanoteknik
Identifikatorer
urn:nbn:se:kth:diva-95416 (URN)10.1088/0957-4484/22/42/425202 (DOI)000295467800003 ()21941036 (PubMedID)2-s2.0-80053281966 (Scopus ID)
Anmärkning
QC 20120524Tillgänglig från: 2012-05-24 Skapad: 2012-05-24 Senast uppdaterad: 2024-03-18Bibliografiskt granskad
6. Size-tuneable synthesis of photoconducting poly-(3-hexylthiophene) nanofibres and nanocomposites
Öppna denna publikation i ny flik eller fönster >>Size-tuneable synthesis of photoconducting poly-(3-hexylthiophene) nanofibres and nanocomposites
Visa övriga...
2012 (Engelska)Ingår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, nr 7, s. 1546-1550Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Poly-(3-hexylthiophene) (P3HT) has been applied in many fields such as organic solar cells, printed electronic circuits, due to superior semiconducting properties compared to other semiconducting polymers. The presence of p-p interaction causes regio-regular P3HT to form ordered lamellar stacks during crystallisation. Here we report a simple room temperature, solution based method to synthesise P3HT nanofibres with controllable sizes. Our method is based on differing solubility of P3HT in various solvents. In a mixed solvent environment, we could control the precipitation of P3HT to obtain nanofibres with various diameters by varying the ratios of the solvents. We found that the lengths of the nanofibres could be controlled with concentration of the solution. Other methods to obtain nanofibres of P3HT invariably involves heating and controlled cooling which makes reproducibility and morphology control difficult. Furthermore, we synthesised a nanocomposite consisting of P3HT nanofibres and quasi-type-II quantum dots and evaluated the photoelectric properties of the nanofibres as well as the nanocomposites using interdigitated gold microelectrodes.

Nyckelord
P3HT, nanofibres, quantum dots, nanocomposites
Nationell ämneskategori
Nanoteknik
Identifikatorer
urn:nbn:se:kth:diva-95407 (URN)10.1002/pssc.201100540 (DOI)000306479300006 ()2-s2.0-84863997565 (Scopus ID)
Konferens
16th International Semiconducting and Insulating Materials Conference (SIMC-XVI) Location: Royal Inst Technol (KTH), Stockholm, Sweden Date: JUN 19-23, 2011
Anmärkning

QC 20121221

Tillgänglig från: 2012-05-24 Skapad: 2012-05-24 Senast uppdaterad: 2024-03-18Bibliografiskt granskad

Open Access i DiVA

fulltext(2997 kB)2085 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 2997 kBChecksumma SHA-512
6ce8c9e53a5189b22e82f60b1baaae24e4d544ca886eaa8287fb587607dcaf701bd801238a418dcb239d630eac6f8619d8f26b634b91a76ee40a70a3179b340c
Typ fulltextMimetyp application/pdf

Sök vidare i DiVA

Av författaren/redaktören
Sugunan, Abhilash
Av organisationen
Funktionella material, FNM
Nanoteknik

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 2088 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

isbn
urn-nbn

Altmetricpoäng

isbn
urn-nbn
Totalt: 688 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf