- Article
Authors: Nguyen, Nang Dinh; Nguyen, Thi Bao Ngoc (2006) - Impedance spectroscopy (IS) technique has been analyzed and
applied to measure the ionic conductivity of the films. For a superionic
conductor, like a thin-film electrolyte, it is necessary to characterize IS by using
a two-electrodes ccll, where the thin film is deposited between two metallic
electrodes. In a very thin film, the Helmholtz layer strongly affects to the
conductivity during the measurement. So that, an equivalent scheme should be
chosen with a separation of three frequency zones to fit the theoretical curves to
experimental data. The best curve fitted with two to three circles is taken and
elaborated to determine all the parameters of the scheme, and R4 — a para...
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- Article
Authors: Nguyen, Nang Dinh; Lam, Minh Long; Hoang, Thi Thu; Huynh, Tri Phong; Tran, Quang Trung (2017) - Graphene quantum dots (GQDs) were synthesized and incorporated with polyethylenedioxythiophene:poly(4-styrenesulfonate) (PEDOT:PSS), Ag nanowires (AgNWs) to form a composite that can be used for enhancement of relative humidity (RH%) sensing. The composite films contained bulk heterojunctions of AgNW/GQD and AgNW/PEDOT:PSS. The sensors made from the composites responded well to relative humidity in a range from 10% to 50% at room temperature. With an AgNWs content ranging from 0.2 wt.% to 0.4 wt.% and 0.6 wt.%, the sensitivity of the relative humidity sensing devices based on AgNWs-doped GQDs+PEDOT:PSS composites was increased from 5.5% to 6.5 % and 15.2 %, respectively. The respon...
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- Article
Authors: Lam, Minh Long; Nguyen, Nang Dinh; Hoang, Thi Thu; Huynh, Tri Phong; Tran, Quang Trung (2017) - Graphene quantum dots (GQDs) were synthesized and incorporated with polyethylenedioxythiophene:poly(4-styrenesulfonate) (PEDOT:PSS), Ag nanowires (AgNWs) to form a composite that can be used for enhancement of relative humidity (RH%) sensing. The composite films contained bulk heterojunctions of AgNW/GQD and AgNW/PEDOT:PSS. The sensors made from the composites responded well to relative humidity in a range from 10% to 50% at room temperature. With an AgNWs content ranging from 0.2 wt.% to 0.4 wt.% and 0.6 wt.%, the sensitivity of the relative humidity sensing devices based on AgNWs-doped GQDs+PEDOT:PSS composites was increased from 5.5% to 6.5 % and 15.2 %, respectively. The respon...
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- Article
Authors: Nguyen, Nang Dinh; Tran, Thi Thao; Do, Ngoc Chung; Vo, Van Truong (2014) - Nanorod-like TiO2 was grown on Ti wafers by annealing at 700oC for 1.5h. Hybrid Organic Solar Cells (HOSC) were then prepared by using a nano hybrid material of P3HT:PCBM/nc-TiO2. The HOSC have the laminar structure of Al/P3HT:PCBM/TiO2/Ti, where P3HT:PCBM weremade by spincoating. Under illumination of the standard light wavelength (l = 470 nm), the polymer luminescence quenching was observed at the heterojunctions, resulting in the charge separation. With an illumination power of 56 mW/cm2, a best hybrid solar cell exhibited an open circuit voltage of 0.60 V, short cut current density of 4.60 mA/cm2, fill factor of 0.54 and photoelectrical conversion efficiency of 2.6 %. This suggest...
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- Article
Authors: Nguyen, Van Thuan; Tran, Vinh Son; Tran, Quang Trung; Tran, Thi Thao; Nguyen, Nang Dinh (2015) - Laser beam diffraction by a patterned surface has been investigated theoretically and experimentally for the determination of the thermal expansion coefficient (a) of polymeric materials. By tracking the deviation of the first order diffraction mode from surface-patterned polymers, expansion coefficients in a range 10-7 to 10-4 K-1 can be measured by temperature changes less than 100 oC. A set-up of laser diffraction (SLD) was made, using a He-Ne laser (l = 632.8 nm) and thin film casting technique. The results of measurements on the SLD system for polymers like PVK polycarbonate, PDMS, organic complex (chitosan) and conducting polymer (P3HT) showed that SLD technique can be applied t...
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- Article
Authors: Tran, Thi Thao; Dang, Hai Ninh; Nguyen, Minh Quyen; Pham, Duy Long; Nguyen, Nang Dinh (2011) - Multilayer thin films of WO3/TiO2/FTO containning inorganic heterojunctions such as TiO2/FTO and WO3/TiO2 were prepared by electro-chemical deposition technique. From the cyclic voltammetry (CV) characteristics one can suggest that in the WO3/TiO2/FTO multi-layer films there is also W-doped TiO2 structure, creating multi-heterojunctions of WO3, TiO2:W, TiO2 and F-doped SnO2. Combining CV, time-current characteristic, in-situ transmittance spectra, the electrochromic performance of WO3/TiO2/FTO was revealed. It is seen that the multi-layer electrochromic devices exhibited much larger electrochromic efficiency and faster response time than that of a standard single layer electrochromic...
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- Journal Article
Authors: Nguyen, Thi Khanh Van; Tran, Si Trong Khanh; Vu, Thi Thao; Nguyen, Duc Cuong; Nguyen, Phuong Hoai Nam; Nguyen, Nang Dinh (2021) - PANI/nc-TiO2/ITO composite films were prepared by electrochemical method where the
monomer aniline was polymerized onto nano-porous TiO2/ITO films (PANI/nc-TiO2/ITO). The
PANI/nc-TiO2 heterojunctions were formed in the composite films due to the insertion of PANI in
nano-porous TiO2 particles. PANI/ITO films exhibited a reversible electrochromic display (ECD)
performance when cycled in 0.1M LiClO4 + propylene carbonate. The response times of the
electrochromic coloration and bleaching of the PANI/nc-TiO2/ITO electrode were 15 s and 20 s,
respectively. Electrochromic efficiency of the films reached a value as large as 12.25 cm2C
-1
.
Taking advantage of the large EC ef...
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- Thesis
Authors: Le, Ha Chi; Advisor: Nguyen, Nang Dinh (2005) - Electrochromic tungsten oxide films can be prepared by a variety of different techniques such as physical vapor [2] and chemical vapor deposition [14,29],electrochemical deposition [13,34], sol -gel [25], etc. The electrochemical deposition is expected to be one of the most economical methods for making a large-area film as well as automatically controlling the film growth. However, these transmittances as well as the durability of the films were still limited for practical use. The aim of this work is to improve electrochromic properties of WO3thin films deposited by electrochemical method. The morphology, electrochemical and optical properties concerning with electrochromic performa...
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- Article
Authors: Do, Ngoc Chung; Nguyen, Nang Dinh; Do, Ngoc Hieu; Pham, Hong Duong (2012) - Nanopowders of cerium doped yttrium aluminum garnet (Y3Al5O12:Ce3+) - YAG:Ce were prepared by low-temperature sol-gel method. High-purity Y2O3, Al(NO3)3.9H2O, Ce(NO3)3·6H2O in the presence of citric acid as complexing agent were used as initial materials. The YAG:Ce nanopowders were characterized using X-ray diffraction, SEM, dynamic light scattering particle size analyzer and a high resolution spectrometer-Microspec-235b. The particle sizes of the YAG:Ce powder were estimated from SEM image and dynamic light scattering particle size analyzer to be 4 – 80 nm. The annealing effect on the crystalline structure of the samples was reported.
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- Article
Authors: Nguyen, Nang Dinh; Tran, Thi Thao; Vu, Nguyen Thuc; Nguyen, Thi Thu Thuy (2010) - Vanadium dioxide films with nano-structured grains have been prepared by RF' sputtering followed by thermal annealing in low oxygen pressure. The submicro-structured crystallini grains with the size of 200 to 250 nm were revealed by FE-SEM micrographs' XRD analysis ptou". the monoclinic lattice of the VO2 crystalline structure and the size of the grains deteimined from XRD also consists of about 200 nm. The temperatwe of the semicoductor tometal phase transition (SMPT) of the films was found at r": 64o9. At temperatures higher than the resistance of the films decreased three orders in magnitude, and the transmittance at l": 1550 nm lowered from 55% to a value as low as 30o/o. From the...
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