Browsing by Author "Lin, Chin-Ching"

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Core-shell CuInS(2)/ZnS quantum dots assembled on short ZnO nanowires with enhanced photo-conversion efficiency
(2009-01-01)
Kuo, Kuan-Ting
;
Liu, Dean-Mo
;
Chen, San-Yuan
;
Lin, Chin-Ching
;
材料科學與工程學系
A novel quantum-dot-based solar cell assembly consisting of core-shell Zn-doped CuInS(2)@ZnS (Zn-CIS@ZnS) quantum dots associated with short ZnO (5 mu m in length) nanowires was developed and systematically investigated in terms of its nanostructure and optical properties, associated with corresponding solar cell parameters, i.e., V(OC), J(SC), fill factor (FF). In this investigation, the photo-conversion efficiency of the Zn-CIS-based solar cells without the presence of the ZnS shell can be readily tuned by controlling the Zn/Cu ratio. Furthermore, the efficiency was significantly improved upon the deposition of a thin ZnS shell on these Zn-CIS QDs, where a significant enhancement in short-circuit current density (J(SC)) by 88% was observed because the ZnS coating is able to effectively eliminate excited electron recombination and enhance the charge transfer efficiency from Zn-CIS QDs to ZnO nanowires. Power-conversion efficiency as high as 0.71% can be attained, which is improved more than 2-3 times compared with that without ZnS coating. Such a unique nanoarchitecture through coupling with both core-shell QDs and short ZnO nanowires suggests a promising design for a quantum dot-based solar cell with considerably improved power-conversion efficiency.
Core-shell CuInS2/ZnS quantum dots assembled on short ZnO nanowires with enhanced photo-conversion efficiency
(2009-01-01)
Kuo, Kuan-Ting
;
Liu, Dean-Mo
;
Chen, San-Yuan
;
Lin, Chin-Ching
;
材料科學與工程學系
A novel quantum-dot-based solar cell assembly consisting of core-shell Zn-doped CuInS2@ZnS (Zn-CIS@ZnS) quantum dots associated with short ZnO (5 mu m in length) nanowires was developed and systematically investigated in terms of its nanostructure and optical properties, associated with corresponding solar cell parameters, i.e., V-OC, J(SC), fill factor (FF). In this investigation, the photo-conversion efficiency of the Zn-CIS-based solar cells without the presence of the ZnS shell can be readily tuned by controlling the Zn/Cu ratio. Furthermore, the efficiency was significantly improved upon the deposition of a thin ZnS shell on these Zn-CIS QDs, where a significant enhancement in short-circuit current density (J(SC)) by 88% was observed because the ZnS coating is able to effectively eliminate excited electron recombination and enhance the charge transfer efficiency from Zn-CIS QDs to ZnO nanowires. Power-conversion efficiency as high as 0.71% can be attained, which is improved more than 2-3 times compared with that without ZnS coating. Such a unique nanoarchitecture through coupling with both core-shell QDs and short ZnO nanowires suggests a promising design for a quantum dot-based solar cell with considerably improved power-conversion efficiency.
Effect of Oxygen on the Microstructural Growth and Physical Properties of Transparent Conducting Fluorine-Doped Tin Oxide Thin Films Fabricated by the Spray Pyrolysis Method
(2013)
Chantarat, N.
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Chen, Yu-Wei
;
Hsu, Shu-Han
;
Lin, Chin-Ching
;
Chiang, Mei-Ching
We reported the fabrication of an FTO conducting thin film via a spray deposition method, which was used to investigate the effect of oxygen content in the carrier gas on deposited film morphology and properties. Using a carrier gas containing various O-2/N-2 concentrations (0%, 20%, 50%, 80%, and 100%) led to significant changes in the thickness, size, and shape of grain growth. The deposited films with 0-50% oxygen content yielded a low resistivity of similar to 10(-4) Omega-cm and a transmittance in the range of 76-96% at 550 nm. Furthermore, by changing the carrier gas concentration, the FTO films displayed different charge transport, recombination, and collection properties due to the surface and interfacial effects. These films with modified properties can be applied to dye-sensitized solar cells (DSSCs). Overall, the conversion efficiency of a solar cell based on a 0% O-2 sample was increased by approximately 2% from that of a 100% O-2 sample. The higher efficiency is mainly the result of the lower O-2 content, which minimized the grain boundaries (spacing) and improved the electron transport on the FTO film surface. (C) 2013 The Electrochemical Society. All rights reserved.
Electron transport behavior of individual zinc oxide coated single-walled carbon nanotubes
(2009-03-11)
Lin, Chin-Ching
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Chu, Bryan T. T.
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Tobias, Gerard
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Sahakalkan, Serhat
;
Roth, Siegmar
Uniform zinc oxide coated single-walled nanotubes (SWNTs) were fabricated by ultrasonic irradiation with acid-treated SWNTs, zinc acetate, and triethanolamine at low temperature in aqueous phase processing. The ZnO coating process did not decrease the dark current of the SWNTs, but a real decrease in the steady state negative photocurrent was observed after ZnO coating, suggesting a clear photosensitization effect. Transport measurements reveal that the negative photocurrent in s (semiconducting)-SWNTs@ZnO could be described by electron-hole compensation behavior attributed to the ZnO layer under ultraviolet excitation. This simple coating method for one-dimensional material can open up new possibilities for multifunctional nanodevices.
Enhanced UV photoresponse in nitrogen plasma ZnO nanotubes
(2009-09-30)
Chantarat, N.
;
Chen, Yu-Wei
;
Chen, San-Yuan
;
Lin, Chin-Ching
;
材料科學與工程學系
The photoresponse behavior of one-dimensional ZnO nanowires (NWs) and nanotubes (NTs) grown on ITO-coated glass substrates via a wet-chemical route was investigated. The photoluminescence spectra exhibited a decrease in the deep-level intensity, indicating that the oxygen defects and impurities are occupied by the presence of N ions in the ZnO NT matrix after a nitrogen plasma treatment. I-V tests demonstrate an enhanced dark current (4.83 x 10(-7) A) after an extended plasma treatment of up to 900s for ZnO NTs compared to that (0.571 x 10(-7) A) of NWs. Furthermore, the ZnO NTs show the highest reliable photoresponse, 20 times that of NWs under UV irradiation (325 nm) in air at room temperature. It is believed that nitrogen plasma ZnO nanotubes can potentially be useful in the designs of 1D ZnO-based solar cells and optoelectronic devices.
Fabrication and Characterization of Mg-Doped ZnO Nanorod Arrays
(2010-07-01)
Liao, Hung-Chou
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Chen, San-Yuan
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Peng, Cheng-Hsiung
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Lin, Chin-Ching
;
Cheng, Syh-Yuh
Photoelectronic characteristics are investigated in well-aligned MgO-coated ZnO nanorods (MgO/ZnO nanocables) grown on Si substrates buffered with ZnO film at a low temperature by solution techniques. Transmission electron microscopy shows that a rough surface was observed for the MgO-coated ZnO nanorods due to deposition of MgO nanoparticles on the surface of the ZnO nanorods. However, after annealed at high temperatures, the surface of the MgO-coated ZnO nanorods was flattened to form Mg-doped ZnO nanorods. Photoluminescence spectra of Mg-doped ZnO nanorods displayed a blue shift of the near-band-edge emission with increasing annealing temperature indicative of an increase in the band gap of the MgZnO alloy due to diffusion of the Mg atoms into the ZnO nanorods. In contrast, no blue shift was detected for the samples annealed in H(2)/N(2) (5%/95%) reduction atmosphere but a blue emission was detected at 800 degrees C, indicating that MgO diffusion process may produce a new luminescent center to emit the blue emission in H(2)/N(2) reduction atmosphere.
High electron injection structure in hybrid solar cells
(2008)
Liao, Hung-Chou
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Chen, San-Yuan
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Lin, Chin-Ching
;
Cheng, Syh-Yuh
;
材料科學與工程學系
We evaluate an ordered organic-inorganic solar cell architecture based on CdS QD-decorated ZnO nanorod arrays encased in the hole-conducting polymer Poly(3-hexylthiophene-2,5-diyl) (P3HT). In this work, CdS quantum dot with different sizes were attached to the surface of the nanorods capped with mercaptopropionic acid. The results show that the CdS QDs on the ZnO nanorods increase both the open circuit voltage (V(OC)) and short circuit current density (J(SC)) relative to devices without CdS QDs. A photovoltaic device based that has been decorated with CdS QDs yields power conversion efficiency over 4 times greater than that for a similar device without CdS QDs. The best device yields a short circuit current density of 1.38 mAcm(-2) under AM1.5 illumination (100 MW cm(-2)), resulting in a power conversion efficiency of 0.21% The increase shows that the modification with CdS QDs can serve not only as a photosensitizer but mainly as an energy funnel and/or an electronic mediator to significantly improve the electron injection efficiency from P3HT to ZnO nanorods.
Improvement in photovoltaic performance for hybrid P3HT/elongated CdS nanocrystals solar cells with F-doped SnO(2) arrays
(2010-01-01)
Liao, Hung-Chou
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Lin, Chin-Ching
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Chen, Yu-Wei
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Liu, Ta-Chung
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Chen, San-Yuan
Hybrid CdS/P3HT photovoltaic devices using F-doped SnO(2) (FTO)-coated ZnO nanorod arrays as electrodes were studied in this work. The crystalline FTO, made using low-cost spray pyrolysis deposition (SPD), displayed a nominally complete and uniform coating over the entire outer surface of the ZnO nanorods. The photovoltaic performance of the CdS/P3HT photovoltaic devices increased with the FTO-coated ZnO nanorod length and thickness of the FTO layer, due to improvement in collecting photogenerated electrons, which results in the increased short circuit current density (J(SC)) and fill factor (FF) of the devices. The incorporation of CdS into the P3HT greatly enhanced the JSC of the devices with a nanorod FTO electrode. The power conversion efficiency (PCE) of the device with a ZnO nanorod length of 320 nm was increased from 0.37% for P3HT without CdS to 1.8% with CdS of AR = 1 (spherical shape). With a further increase of the AR of the CdS nanocrystal to 4, the PCE was further increased up to 2.6%. However, longer CdS nanocrystals conversely caused deterioration in PCE as a result of the nanorod array morphology. These results indicate that, although increased nanorod length could improve the photocurrent and efficiency, other factors, such as P3HT infiltration, nanorod array morphology and CdS nanocrystal length are required for obtaining the optimal performance of these devices.
Improvement in photovoltaic performance for hybrid P3HT/elongated CdS nanocrystals solar cells with F-doped SnO2 arrays
(2010-01-01)
Liao, Hung-Chou
;
Lin, Chin-Ching
;
Chen, Yu-Wei
;
Liu, Ta-Chung
;
Chen, San-Yuan
Hybrid CdS/P3HT photovoltaic devices using F-doped SnO2 (FTO)-coated ZnO nanorod arrays as electrodes were studied in this work. The crystalline FTO, made using low-cost spray pyrolysis deposition (SPD), displayed a nominally complete and uniform coating over the entire outer surface of the ZnO nanorods. The photovoltaic performance of the CdS/P3HT photovoltaic devices increased with the FTO-coated ZnO nanorod length and thickness of the FTO layer, due to improvement in collecting photogenerated electrons, which results in the increased short circuit current density (J(SC)) and fill factor (FF) of the devices. The incorporation of CdS into the P3HT greatly enhanced the JSC of the devices with a nanorod FTO electrode. The power conversion efficiency (PCE) of the device with a ZnO nanorod length of 320 nm was increased from 0.37% for P3HT without CdS to 1.8% with CdS of AR = 1 (spherical shape). With a further increase of the AR of the CdS nanocrystal to 4, the PCE was further increased up to 2.6%. However, longer CdS nanocrystals conversely caused deterioration in PCE as a result of the nanorod array morphology. These results indicate that, although increased nanorod length could improve the photocurrent and efficiency, other factors, such as P3HT infiltration, nanorod array morphology and CdS nanocrystal length are required for obtaining the optimal performance of these devices.
Mechanism of an AZO-coated FTO film in improving the hydrogen plasma durability of transparent conducting oxide thin films for amorphous-silicon based tandem solar cells
(2012)
Chantarat, N.
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Hsu, Shu-Han
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Lin, Chin-Ching
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Chiang, Mei-Ching
;
Chen, San-Yuan
An Al-doped ZnO (AZO)/F-doped SnO2 (FTO) film structure in an amorphous silicon solar cell (a-Si: H) was studied under exposure to hydrogen (H) plasma treatment via a simple spray pyrolysis. A radio-frequency magnetron sputtering method was used to deposit the FTO film first and the subsequent AZO overlayer on top of the FTO. The results of this approach suggest that the AZO film acts as a protection layer for the underlying FTO film and thus provides an excellent interface that protects the film from the direct bombardment with H+ ions and radicals. Even under exposure to H-plasma, the optical (UV-Vis) and electrical properties (Hall measurement) of the AZO/FTO double layer film show improvement in plasma stability in comparison with a single FTO film. Without the AZO overlayer, the reduction of SnO2 to metallic Sn and sub-oxidized SnO can occur in the FTO film. However, after a post-annealing treatment at 400 degrees C, the degradation of the FTO can be reversed by reoxidizing the Sn-O bonds. This interpretation of the H+ ion diffusion and the Sn-O redox process is confirmed via XPS and SIMS analysis. This investigation provides an opportunity to study the H+ ion diffusion mechanism in a metal oxide matrix in the presence of plasma and thermal effects. The study thus provides an alternative to the conventionally used FTO-based Si solar cells.
Nitrogen Plasma-Assisted Codoped P-type (In, N):SnO(2) Ultra-Fine Thin Films and N-ZnO/p-In:SnO(2) Core-Shell Heterojunction Diodes Fabricated by an Ultrasonic Spray Pyrolysis Method
(2011-11-24)
Chantarat, N.
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Chen, Yu-Wei
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Lin, Chin-Ching
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Chiang, Mei-Ching
;
Chen, Yu-Chun
In this study, tin oxide (SnO(2)) solution mixtures containing indium (In) of 0%, 3%, 7%, 15%, and 30% were used to fabricate In- and N-codoped SnO(2) films on glass at 400 degrees C using an ultrasonic spray pyrolysis method combined with thermal annealing at 600 degrees C and post nitrogen plasma treatment. X-ray diffraction analysis demonstrated that the incorporation of elemental In in the SnO(2) film primarily induces the evolution of crystalline phases from In-doped SnO(2) to Sn-doped In(2)O(3), depending on the doping concentration. Upon exposure to N plasma, the dark current dramatically increases in proportion to the treatment duration (5-40 min); the dark current can be enhanced for the 3% and 7%-doped samples by as much as 3 orders of magnitude compared to the untreated samples. Hall measurements confirmed that hole carriers could dominate the SnO(2) host matrix to promote p-type properties at a low In content (3% and 7%) with an increase in resistance compared to undoped samples. However, samples with higher In content (15% and 30%) showed the opposite trend, due to the formation of a secondary phase of n-type In(2)O(3). X-ray photoelectron spectroscopy was used to probe the incorporation and dissociation of chemical bonds between the doped In and N atoms in the SnO(2). Moreover, depth profile measurements showed a correlation between the elemental compositions and elemental distributions of the codoped SnO(2) film. Current-voltage (I-V) characterization revealed the improved behavior of heterojunction diodes consisting of a p-type (In, N)-doped SnO(2) thin film deposited on n-type ZnO nanorod arrays.
Nitrogen Plasma-Assisted Codoped P-type (In, N):SnO2 Ultra-Fine Thin Films and N-ZnO/p-In:SnO2 Core-Shell Heterojunction Diodes Fabricated by an Ultrasonic Spray Pyrolysis Method
(2011-11-24)
Chantarat, N.
;
Chen, Yu-Wei
;
Lin, Chin-Ching
;
Chiang, Mei-Ching
;
Chen, Yu-Chun
In this study, tin oxide (SnO2) solution mixtures containing indium (In) of 0%, 3%, 7%, 15%, and 30% were used to fabricate In- and N-codoped SnO2 films on glass at 400 degrees C using an ultrasonic spray pyrolysis method combined with thermal annealing at 600 degrees C and post nitrogen plasma treatment. X-ray diffraction analysis demonstrated that the incorporation of elemental In in the SnO2 film primarily induces the evolution of crystalline phases from In-doped SnO2 to Sn-doped In2O3, depending on the doping concentration. Upon exposure to N plasma, the dark current dramatically increases in proportion to the treatment duration (5-40 min); the dark current can be enhanced for the 3% and 7%-doped samples by as much as 3 orders of magnitude compared to the untreated samples. Hall measurements confirmed that hole carriers could dominate the SnO2 host matrix to promote p-type properties at a low In content (3% and 7%) with an increase in resistance compared to undoped samples. However, samples with higher In content (15% and 30%) showed the opposite trend, due to the formation of a secondary phase of n-type In2O3. X-ray photoelectron spectroscopy was used to probe the incorporation and dissociation of chemical bonds between the doped In and N atoms in the SnO2. Moreover, depth profile measurements showed a correlation between the elemental compositions and elemental distributions of the codoped SnO2 film. Current-voltage (I-V) characterization revealed the improved behavior of heterojunction diodes consisting of a p-type (In, N)-doped SnO2 thin film deposited on n-type ZnO nanorod arrays.
Photoconductive Enhancement of Single-Layer Tin Oxide-Coated ZnO Nanowires
(2010)
Lin, Chin-Ching
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Chen, Yu-Wei
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Chiang, Mei-Ching
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Lee, Chia-Hua
;
Tung, Yung-Liang
In this study, zinc oxide nanowires (ZnO NWs) coated with crystalline tin oxide (SnO(2)) by an ultrasonic spray pyrolysis were investigated. High resolution transmission electron microscopy analysis confirms that a continuous single SnO(2) layer of about 10 nm has been coated on the ZnO NWs. Photoconductivity measurements revealed that the ZnO NWs coated with the single uniform SnO(2) layer had a higher photoconductivity ratio by about a factor of 8 compared to the pristine ZnO NWs, attributed to the multi-photoexcited electrons. Under a steady radiation of UV light (lambda=325 nm), a substantial increase in the steady-state photocurrent is noticeable, suggesting that extra photoinduced charges are transferred from SnO(2) to ZnO NWs.
RETRACTION: Nucleation and growth behavior of well-aligned ZnO nanorods onorganic substrates in aqueous solutions (Retraction of Vol 283, Pg 141, 2005)
(2018-12-15)
Lin, Chin-Ching
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Chen, San-Yuan
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Cheng, Syh-Yuh
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材料科學與工程學系
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Department of Materials Science and Engineering
Selective Oxygen-Plasma-Etching Technique for the Formation of ZnO-FTO Heterostructure Nanotubes and Their Rectified Photocatalytic Properties
(2010-12-06)
Chantarat, N.
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Chen, Yu-Wei
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Lin, Chin-Ching
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Chiang, Mei-Ching
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Chen, San-Yuan
A novel ZnO-FTO heterostructure nanotube array was produced by combining a chemical solution process with oxygen-plasma etching. In this approach, presynthesized ZnO nanorod arrays act as templates, and FTO nanoparticles are deposited onto the ZnO nanorods by a simple spray pyrolysis method. X-ray photoelectron spectroscopy analysis demonstrated that the oxygen-plasma treatment decreased the O(2-)/OH(-) concentration ratio, resulting in dissociation of the Zn-O bonds and the outward diffusion of Zn cations to form an interior hollow, which is related to the formation of the hydroxyl functional group, Sn-OH, at the FTO surface. An etching evolution mechanism of the ZnO-FTO nanotubes via oxygen plasma was tentatively proposed in this study. Time-dependent photocurrent (I-T) measurements under ON-OFF cycles of UV illumination confirm that the 20-min etched sample exhibits a rectified photoresponse characteristic and a dark current increased by about 3 orders of magnitude over that of the unetched sample, which is attributed to the increased carrier concentration created at the surface conductive layer. This investigation offers an alternative selective etching method to lay the framework for nanoscale three-dimensional electrodes for solar-cell applications.
Study on luminous phosphor with improved luminous efficiency for plasma planar backlight
(2005)
Lin, Chin-Ching
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Lee, Shu-Ping
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Kuo, Kuan-Ting
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Chen, San-Yuan
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Hsieh, Hank
Highly luminescent efficiency white-light phosphors have been successfully produced by microwave irradiation treatment. The SEM image and XRD analysis reveal that the surface morphology of the white-light phosphors can be notably modified by microwave irradiation from sheet-like into spherical shapes and exhibit with better crystalline property. The VUV PL spectra show that the microwave irradiation treatment can effectively enhance the luminescent efficiency by a factor of 1.5 times for intensity in comparison with that without microwave treatment. The improvement in all visible emission can he related to the modified surface morphology and increased crystalline properties of the white-light phosphors. These results demonstrate that such a simple approach can provide for the fabrication of highly luminescent efficiency phosphors for the optoelectronic devices.
Synthesis and characterization of highly luminescent CuInS(2) and CuInS(2)/ZnS (core/shell) nanocrystals
(2008-12-01)
Kuo, Kuan-Ting
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Chen, San-Yuan
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Cheng, Bing-Ming
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Lin, Chin-Ching
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材料科學與工程學系
High-quality CuInS(2)/ZnS (core-shell) nanocrystals (NCs) were synthesized via a colloidal solvent process and characterized for their optical properties by UV-vis, room temperature solution photoluminescence (PL) spectroscopy, and further obtained powders were characterized by X-ray microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS). diffraction (XRD), transmission electron The obtained CIS and CIS/ZnS core/shell NCs are quasimonodisperse with an average particle size of 2.4 and 4.6 nm, respectively. All of the as-synthesized NCs can be well dispersed in toluene or hexane to form stable and clear colloidal solutions, which show strong visible emission (blue for CIS/ZnS core/shell NCs) under UV excitation. The growth of a ZnS shell on CIS NCs, that is, the formation of CIS/ZnS core/shell NCs, resulted in an impact enhancement in the PL intensity compared to that of bare CIS NCs due to the eliminated surface defects and the reduced lattice mismatch between the core and shell materials. A dramatic increase of the PL intensity can be obtained from the ZnS-capped CIS with respect to that of the bare CIS NCs. (C) 2008 Elsevier B.V. All rights reserved.
Synthesis and characterization of highly luminescent CuInS2 and CuInS2/ZnS (core/shell) nanocrystals
(2008-12-01)
Kuo, Kuan-Ting
;
Chen, San-Yuan
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Cheng, Bing-Ming
;
Lin, Chin-Ching
;
材料科學與工程學系
High-quality CuInS2/ZnS (core-shell) nanocrystals (NCs) were synthesized via a colloidal solvent process and characterized for their optical properties by UV-vis, room temperature solution photoluminescence (PL) spectroscopy, and further obtained powders were characterized by X-ray microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS). diffraction (XRD), transmission electron The obtained CIS and CIS/ZnS core/shell NCs are quasimonodisperse with an average particle size of 2.4 and 4.6 nm, respectively. All of the as-synthesized NCs can be well dispersed in toluene or hexane to form stable and clear colloidal solutions, which show strong visible emission (blue for CIS/ZnS core/shell NCs) under UV excitation. The growth of a ZnS shell on CIS NCs, that is, the formation of CIS/ZnS core/shell NCs, resulted in an impact enhancement in the PL intensity compared to that of bare CIS NCs due to the eliminated surface defects and the reduced lattice mismatch between the core and shell materials. A dramatic increase of the PL intensity can be obtained from the ZnS-capped CIS with respect to that of the bare CIS NCs. (C) 2008 Elsevier B.V. All rights reserved.
Synthesis and luminescent properties of strong blue light-emitting Al2O3/ZnO nanocables
(2008)
Hsiao, Chi-Sheng
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Kuo, Wan-Lin
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Chen, San-Yuan
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Shen, Ji-Lin
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Lin, Chin-Ching
Photoelectronic characteristics are investigated in well-aligned aluminum-coated ZnO nanorods (Al2O3/ZnO nanocables) grown on Si substrates buffered with ZnO film at a low temperature. Photoluminescence measurement indicates that a strong blue emission peak at similar to 450 nm appears at 400 and 600 degrees C in O-2 and N-2 atmospheres, respectively. A 30x enhancement of the relative intensity ratio of blue emission (I-B) to ultraviolet emission (I-UV) has been observed for the Al2O3/ZnO nanocables. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy analyses reveal that the origin of the strong blue emission can be attributed to the structure transition and cleavage of the oxygen-hydrogen bond (OH) of the Al2O3/ZnO nanocable, which leads to the formation of singly ionized oxygen vacancies (Al-O-center dot). (C) 2008 The Electrochemical Society.
Synthesis and optical properties of white-light-emitting alumina/ZnO nanotubes
(2008-10-08)
Hsiao, Chi-Sheng
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Chen, San-Yuan
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Kuo, Wan-Lin
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Lin, Chin-Ching
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Cheng, Syh-Yuh
A simple chemical solution process was used to prepare alumina nanoparticle-coated ZnO nanotubes (ANZTs). Transmission electron microscope (TEM) images proved that the alumina nanoparticles were uniformly dispersed on the ZnO nanotubes. After thermal treatment at different temperatures under various atmospheres, photoluminescence (PL) measurements showed that the ANZTs emitted a variety of colors, including blue, green and white light. Gaussian curve fitting of the PL spectra revealed that the competition between the blue, blue-green, green and yellow band emissions and their relative emission intensities were strongly associated with various defects. Blue emission was attributed to large numbers of oxygen defects in alumina, while green and yellow emissions were related to oxygen and zinc defects in ZnO, respectively. Under specific conditions, white light, consisting of blue, blue-green, green and yellow band emissions, was obtained. Further TEM analysis indicated that the defect structure of ANZTs could be manipulated by the interface interaction between alumina and the ZnO nanotubes.