Kuo-Ting Huang

Electrochromic and optical properties of tungsten oxide films deposited with DC sputtering by introducing hydrogen

Research was undertaken to investigate the electrochromic and optical properties of tungsten oxide (WO3) films deposited by introducing hydrogen with a direct current (DC) and pulsed DC sputtering. The results show that WO3 films have optimum electrochromic properties at a hydrogen flow of 4 and 3 sccm for DC and pulsed DC, respectively. In the Raman spectra, the peak intensity increased with the increase of hydrogen flow at both 770  cm1 and 950  cm(-1) peaks, which resulted in bonds of W(6+)-O and W(6+)=O, respectively. Simultaneously, the transmittance (ΔT550  nm) variations were 65.6% and 64.4%, and the average transmittance (ΔT400-500  nm) variations were 56.7% and 56.4% for DC and pulsed DC, respectively. The bleached/colored ability of the cyclic voltammograms (CVs) was DC>pulsed DC, and the resistances of AC impedance were pulsed DC>DC.

Measurement of residual stress for ITO/PET substrates by the double beam shadow moiré interferometer

This study constructed a measurement system that can quickly and accurately analyze the residual stress of flexible electronics. A double beam shadow moiré interferometer was set up to measure and evaluate the residual stress of tin-doped indium oxide films on a polyethylene terephthalate substrate. However, this system required only two symmetrical fringes to evaluate the residual stress of transparent conductive oxide films on flexible substrate. Applying the grating translation techniques to the double beam shadow moiré interferometer greatly improved the measurement resolution and accuracy, and the relative error was reduced to 1.2%.

Precision improving of double beam shadow moiré interferometer by phase shifting interferometry for the stress of flexible substrate

While tin-doped indium oxide (ITO) has been extensively applied in flexible electronics, the problem of the residual stress has many obstacles to overcome. This study investigated the residual stress of flexible electronics by the double beam shadow moiré interferometer, and focused on the precision improvement with phase shifting interferometry (PSI). According to the out-of-plane displacement equation, the theoretical error depends on the grating pitch and the angle between incident light and CCD. The angle error could be reduced to 0.03% by the angle shift of 10° as a result of the double beam interferometer was a symmetrical system. But the experimental error of the double beam moiré interferometer still reached to 2.2% by the noise of the vibration and interferograms. In order to improve the measurement precision, PSI was introduced to the double shadow moiré interferometer. Wavefront phase was reconstructed by the five interferograms with the Hariharan algorithm. The measurement results of standard cylinder indicating the error could be reduced from 2.2% to less than 1% with PSI. The deformation of flexible electronic could be reconstructed fast and calculated the residual stress with the Stoney correction formula. This shadow moiré interferometer with PSI could improve the precision of residual stress for flexible electronics.

Using Artificial Neural Networks Approach for the Color Enhance of High Power LEDs

High power light-emitting diodes (HP-LEDs) always are applied for energy-saving to replace the traditional light sources. HP-LEDs lighting has been regarded in the next generation lighting. In this study, the RGY colors enhance of whit LED lighting was researched and modulated by artificial neural network (ANN). An ANN model was used to investigate the correlated color temperature (CCT) and luminous flux (Lux) for the white LED enhanced with different power of single RYG LEDs. The starting color temperature of the white LED will be set at 7500K (D75 white light standard), then changed the voltage of the single LED of the red, green or yellow, respectively, to find the best tuning function for the color temperature and luminous efficiency. These results exhibited that changing the voltage of red LED had the broader color temperature from 7500 K to 1500 K than the range of green and yellow LEDs from 7500K to 8200K and 7500K to 4700K, respectively. Then, these experimental results were used as input data for the training model. After the learning model was completed, an analysis was used to obtain the internal representation of the color information by the responses of the individual chips of the three hidden units in the middle layer. Identification rate of data would be achieved to 100% by the neural network pattern-recognition tool. Anyway, the correlation coefficient could reach to 99% by the ANN fitting tool for the color enhancement.

Separation of the semiconducting and the metallic types of single-wall carbon nanotube by electrophoresis method

This study was to separate the semiconducting and the metallic types of single-wall carbon nanotubes (SWNTs) by electrophoresis with the different dispersants that are deoxyribonucleic acid (DNA), Triton X-100 and sodium dodecyl sulfate (SDS), respectively. The dispersants modify the surface of SWNTs and disperse in the de-ionized water. and used electric power supply 100V to electrophoresis. However, the different dispersants such as DNA, Triton X-100 and SDS coated on SWNTs have different property of electronic field. Hence, in the same power of electrophoresis was applied to separate out s-SWNT and m-SWNT from the raw-SWNT. In addition, the DNA base pair and quantitative can be determine by electrophoresis with standard mark. The electrophoresis has features that low sample need, low energy required and efficiently for this fabrication. The results of Raman spectrum could verify the separation efficiency and determine the electrical of the samples with the radial breathing mode (RBM, 100-400cm-1) of SWNT. After the dispersion process with DNA, a new peak (~1450 cm-1) has been observed between D-band (~1350cm-1) and G-band (~1550cm-1) that also can identify s-SWNT and m-SWNT.

Microstructure Property of CNTs Deposited on Nickel Foam by CVD with Different Ni Catalytic Seed for Flexible PV

There are three different preparations of the Ni catalytic seed for the CNT/NiF layer. The results exhibited Ni catalytic could affect the growth of CNTs on NiF by SEM and Raman spectra.

Electrochromic and optical properties of tungsten oxide films deposited with DC sputtering by introducing of hydrogen

Tungsten oxide (WO3) films deposited with DC sputtering by introducing of hydrogen were investigated the electchromic and optical properties. The coloration efficiency of WO3 films would increase with the increasing of hydrogen flow in deposition.

Transparent conducting carbon nanotubes thin films on the flexible substrate

This study investigated the application of single-wall carbon nanotubes( SWCNTs) on transparent conducting film. The SWCNTs films deposited on the flexible substrate using dip-coating. The major issue was studying the time and temperature of sulfuric acid effect on the pretreatment of SWCNTs. The post-treatment of etching dispersion and how to affect the optical and sheet resistance were always considered. The results showed that the sheet resistance of SWCNTs under 12 hrs pretreatment was higher than that without pretreatment, but over 12hrs the sheet resistance was lower than that without pretreatment. The sheet resistance of SWCNTs over 120°C pretreatment temperature was higher than that of pristine, but the sheet resistance of SWCNTs below 120°C pretreatment temperature was lower than that of pristine. Simultaneously, the dispersion combined with the functional group consisting of acetic acid (-OOH) could make SWCNTs to be more dispersion than before. Pretreatment of sulfuric acid at temperature of 120°C and time of 24 hrs had the good performance on optical and electricity for SWCNTs film. And the sheet resistance of SWCNTs film could reach 781 Ω/sq at transmittance of 70%. This study investigated the mechanism of the pretreatment of the dispersing and acid destroying for SWCNTs. An optimized acid pretreatment was used to improve the transparent and electricity on the flexible substrate with SWCNTs.

Investigation of the optical and structural properties of WO3 thin films with different sputtering power supplies

The purpose of this research was to investigate the optical and structural properties of tungsten oxide (WO3) thin films deposited with three different sputtering power supplies: direct current (DC), DC pulse and radio frequency (RF). These WO3 thin films were deposited on ITO glass and silicon substrate with different gas ratios of oxygen and argon (O2/Ar ratio). WO3 thin film is the role of the electrochromic window was resulted from the advantages of large variation in optical density, high response efficiency, no toxicity and low cost. The experimental results showed that optical intensity increased with the increasing of O2/Ar ratio and all films have the 950cm-1 peak which the bonding of W+6=O in Raman spectra. Hence, the O2/Ar ratio was changed from 0.4 to 0.8 to study the ability of coloring and bleaching for the three different power supplies. Anyways, the WO3 thin films had the best electrochromic property at the O2/Ar ratio of 0.7, 0.6 and 0.6 for DC, DC pulse, and RF, respectively. The transmittances could be over 75% for all films at as-deposited and the deposition rates were between 0.8 and 0.1 Ås-1. Simultaneously, the transmittance variations (ΔT) were 51%, 57% and 53% for DC, DC pulse, and RF power sources at wavelength of 550 nm, respectively. The coloration ability of WO3 thin film deposition with power supply of DC pulse was better than that of the DC and RF.

Measuring the residual stress of transparent conductive oxide films on PET by the double-beam shadow Moiré interferometer

The purpose of this research was to construct a measurement system which can fast and accurately analyze the residual stress of the flexible electronics. The transparent conductive oxide (TCO) films, tin-doped indium oxide (ITO), were deposited by radio frequency (RF) magnetron sputtering using corresponding oxide targets on PET substrate. As we know that the shadow Moiré interferometry is a useable way to measure the large deformation. So we set up a double beam shadow Moiré interferometer to measure and analyze the residual stress of TCO films on PET. The feature was to develop a mathematical model and combine the image processing software. By the LabVIEW graphical software, we could measure the distance which is between the left and right fringe on the pattern to solve the curvature of deformed surface. Hence, the residual stress could calculate by the Stoney correction formula for the flexible electronics. By combining phase shifting method with shadow Moiré, the measurement resolution and accuracy have been greatly improved. We also had done the error analysis for the system whose relative error could be about 2%. Therefore, shadow Moiré interferometer is a non-destructive, fast, and simple system for the residual stress on TCO/PET films.