Polymer light emitting diodes (PLED) were using a heterocyclic aromatic rigid-rod polymer poly-p-phenylene-benzobisoxazole (PBO) as an opto-electronically active layer; and poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) as a hole transporting layer. Aluminum (Al) and indium tin oxide (ITO) were served as device cathode and anode, respectively. [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) or derivatized multi-wall carbon nano-tube (MWCNT-C18), with great electron transporting ability, was doped into PBO to enhance the performance of PLED devices as well as the thin-film electrical conductivity. The optical length was changed by using different spin coating speeds and durations. From the research, the £fmax of electroluminescence (EL) was blue-shifted as PEDOT:PSS spin coating speed increased for a thinner layer. Once using a higher spin coating speed repeatedly to coat PEDOT:PSS, the £fmax of electroluminescence was red-shifted. If the PEDOT:PSS film thicknesses were similar, the EL spectra were almost the same, independent of device processing scheme. The injection current and EL intensity were enhanced by doping PC61BM or MWCNT- C18. The electric conductivity parallel to film surface (£m¡ü) was increased as the doping concentration increased. Because of the extremely different aspect ratio, the MWCNT-C18 had a lower percolation threshold concentration. Therefore, at a low MWCNT-C18 doping concentration, the injection current and the EL intensity were enhanced compared with those of PC61BM.

A high efficiency driver circuit is proposed for Light Emitting Diode (LED) lamps with dimming feature. The current regulation is accomplished by processing partial power of the power conversion circuit so that a high overall efficiency can be realized. The detailed description and analysis of circuit operation are provided. The dimming feature can be accomplished by means of linear current regulation, pulse-width modulation (PWM) or double pulse-width modulation (DPWM). Based on the circuit analyses and derived equations, a laboratory circuit is designed for an LED lamp which is composed of 40 high-brightness white LEDs in series. The performances with three dimming schemes are compared from the measured results. LEDs dimmed by DPWM have less color shift than those dimmed by linear current regulation and PWM. On the other hand, the dimming scheme with linear current regulation has the highest light efficiency over the entire dimming range. The circuit efficiency can be as high as 95.5% at the rated output and deteriorates slightly to 90.5% as the lamp is dimmed to 10% of the rated power.

Halogen lamps are mostly applied as a light source to the traditional lamp for medical treatment due to its proper color temperature, but it has its disadvantages such as ultraviolet rays and infrared rays which will be harmful to the patients and faculties in the hospitals under long-term exposure. Consequently, using light emitting diode(LED) as a new light source instead of the traditional halogen lamp will be the trend of the future. The purpose of this study is to design a projective LED dental lamp that can achieve the goals of 200mm¡Ñ100mm for light shape and 11000lux illuminance energy by using the optics simulation software, LightTools. Firstly, a single LED lamp module with a high focusing hollow tubular light guide structure was designed and developed comparing with the solid light guide structure used in many commercial projective dental lamp, the hollow tubular light guide structure can decrease illuminance energy lose due to the absorption by tube material. Because the required objective light shape could not be achieved by using the designed light guide structure only, so a lens component was adopted and designed in order to shrink the output light shape to the required size. Finally, through the specific arrangement of position and angle of each LED lamp module, a projective LED dental lamp with 9 LEDs lamp modules which conform with the required illuminance energy was proposed.

This thesis proposes a dimming approach with Double Pulse Width Modulation for equalizing the light output of the back light with light emitted diodes (LEDs) for large scale outdoor liquid crystal displays (LCDs). The approach compensates the difference among the LED light bars by adjusting the power outputs of converters according to the feedback of light strength from light sensors. With the proposed Double Pulse Width Modulation method, local brightness adjustment on the light bars can be made to provide a uniform light output and the dimming function for LCD can be retained. Experiments results made on a 46¡¨ LCD with four LED light bars demonstrate that the double pulse-width- modulation can provide uniformly in the light bar output. The experimental results show the proposed Double Pulse Width Modulation (DPWM) method can alleviate the problem from divergence of the light bars and thus can generate more uniform light output on LCDs.

In this thesis, we have reported the MBE growth, design, and fabrication of the InGaAs quantum dots (QDs) laser/semiconductor optical amplifier, broadband QDs structure, coupled double cavity structure for terahertz emission on GaAs substrate. The emission wavelengths of the strain-induced S-K growth mode QDs structures are adjusted through the composition of QDs and strain-compensated capping layer. Also, the technique of growing high quality InGaAs QDs with solid source molecular beam epitaxy has been established and characterized by double crystal X-ray diffraction, transmission electron microscopy, photoluminescence, electroluminescence measurements. For 1.3£gm QDs laser samples, ridge waveguide lasers of the Fabry-Perot (FP) type are fabricated by wet-etching process. From the QDs laser L-I curve, the e2-hh2 transition at £f =1160nm have larger optical gain than e1-hh1 transition at £f =1220nm. The FP laser with 0.6£gm cavity length shows a lasing peak of 1160nm at threshold. As the cavity length increase to 2£gm, the lasing peak red shift to 1220nm (closed to ground state emission wavelength). This energy band gap transition phenomenon is obvious especially in the QDs laser with quantum well (QW) structure. When the injection current increase, two lasing peaks at £f= 1160 and 1175nm are observed sequentially. This unique lasing behavior is shown to be consistent with carriers localized in noninteracting dots. For the application of 1.3£gm light source, we optimum the growth condition for different needs in optical coherent tomography (OCT) light source, tandem solar cell, terahertz emission light source, etc. For the super luminescence diode (SLED) in OCT, we design multi-stacked asymmetric QDs structure (AMQD), QDs in the well structure (DWell), Dwell with p-doping in well structure to investigate the carrier recombination condition and bandwidth. Comparing with 5 structures in this study, the Dwell with p-doping in well structure has a maximum EL bandwidth exceed 198nm. The large bandwidth is attributed to the QW which increases the carrier capture rate and the p-doping which provide the efficient holes in valance band. This structure provides an excellent SLED light source solution to replace the existing program. For the tandem solar cell, we use the multi-stack QDs to compose broadband absorption in 1eV range. In order to avoid the degradation in the open circuit voltage, we use InGaAs QW to reduce the QDs strain. We observed the doping effect on the built in field through the photo-reflectance measurements. For the better photocurrent collection, we use p-doping in the QW to increase the built-in field intensity to obtain higher efficiency. For the terahertz emission, the QDs embedded in coupled double-cavity structures with an AlAs/GaAs intermediate distributed Bragg reflector (DBR) are grown on GaAs substrates. Two emission peaks at 1180, 1206 nm from the QDs corresponding to the coupled double-cavity resonant modes are observed in the high reflection band. The frequency differences for the two resonant coupled modes are of 5.5 terahertz, and have been successfully controlled by changing the pair numbers for the intermediate DBR. In addition, we have grown the InGa(Al)As nanostructures on InP substrate. The lattice constant difference between InGaAs and InP is relatively smaller compare with GaAs substrate, and it will be more challenge in epitaxial growth. After we investigate the strain, surface morphologies, optical properties for the nanostructures, we find the group III elements play an important role in the morphologies. Wire formation is attributed by the enhanced adatom diffusion length in the stepped surface front along [0-11] direction for the presence of Ga both in the nanostructure and buffer layer. Finally, we established QDs, Qwires database for the valuable new possibilities for designing new and original structures.

In this thesis, a novel blue Poly (arylene ether) s polymer was prepared for the organic polymer light emitting diodes which was composed of the main material anthracene difluoro monomer derivatives, and object material of triphenylamine with the extension structure similar to the literature seen BD-1 asymmetric derivatives, as the hole transport material of carbazole of the diol derivatives. In general, Anthracene derivatives and BD-1, often seen in the literature as the host, guest blue polymer doping, the main use to Forster energy transfer to transfer energy to the guest, so it has good luminous efficiency. Anthracene, flat Good, easy to crystallization during evaporation, resulting in leakage generated; and the deposition of the multilayer structure will hinder charge injection to the emitting layer. From the angle of the molecular design of this study. (1) Use of the CF bond and Carbazole increase the steric hindrance of the polymer chain and change by fluoride compounds of the highest occupied molecular orbital - lowest unoccupied molecular orbital energy level. (2) The hole transport layer to import into the emitting layer. The two monomers Anthracene derivatives fluoride monomer the Carbazole of diol derivatives via nucleophilic polycondensation synthesis of a novel in proper proportion, Blue polymer. Component parts, the Blue poly aromatic ether polymer doped with a small amount of blue light-emitting guest as a component layer of the component structure: ITO / PEDOT: PSS / emitting layer / LiF / Al light-emitting layer can make use of spin coating of solvent process, and its advantage is the convenience of the process and a large area. The undoped guest before the Blue polymer production the PLED starting voltage can be reduced to 4.5 V, and maximum brightness 7 466 cd/m2, efficiency as high as 4.2 cd / A. C.I.E. coordinates of (0.15,0.08), very close to the official regulations of the NTSC Blue coordinates (0.14,0.08). When doped with 3% of the guest, the starting voltage can be reduced to 4.5 V, maximum brightness of 12104 cd/m2 and efficiency as high as 5.79 cd/A.

The temperature and thermal stress distributions and variations of the high power LED module were studied in this work. The thermal-elastic-plastic 3D finite element models of MSC.marc software package are employed to simulate these performances for the high power LED module. Two high power white light LED module designs are investigated¡G one is the traditional phosphorescent silicone with blue LED module and the other is a phosphor glass lens with blue LED module. The distributions of temperature and thermal stress of in these two operating LED modules are compared and discussed. The effects of different packaging parameters¡Ge.g. bonding materials, substrate materials, lens materials on the temperature and thermal stress have also been studied in this work. The simulated results reveal that the serious thermal crack may occur for these two designs if the power of single die is over 10 watt. The simulated results also indicate that an attached fin cooler may improve these thermal crack disadvantaged significantly. The effect of fin design parameters on the peak temperature reduction has studied. A feasible fin design for the high power LED module has also been proposed.

The background and motivation of this study are based on: (1) Energy saving and carbon emission reduction are the rising issues gaining more awareness and efforts worldwide. (2) Taiwan plans to build ¡§low-carbon cities¡¨ in order to implement the policy of greenhouse gas reduction. (3) The most direct and practical way to reduce carbon emissions is by saving energy. (4) Everyone has to use illumination sources. (5) ¡§Electro-Magnetic Induction Lamps¡¨ is a useful tool to achieve the goal of energy saving and carbon emission reduction. Thus the topic of this study is ¡§The Effectiveness Analysis and Strategy of Energy-efficient Lighting in Developing a Low Carbon City ¡V A Case on Electro-Magnetic Induction Lamps¡¨. The objectives of this study are: 1. To analyze the characteristics of ¡§Electro-Magnetic Induction Lamps¡¨ and their conformity with local and overseas energy-efficient lighting policies. 2. To analyze the effectiveness of lighting economics of the case companies before and after their adoption of ¡§Electro-Magnetic Induction Lamps¡¨. 3. To explore the possible obstacles and their solutions for lighting industry development of ¡§Electro-Magnetic Induction Lamps¡¨ in the public sectors¡¦ strategies to develop low-carbon cities in Taiwan. The main issues of this study are about energy-efficient lighting policies and the economical effectiveness of ¡§Electro-Magnetic Induction Lamps¡¨, which belong to policy research on energy-saving equipment and the lighting industry. Therefore three research methods: Literature Review, Case Study, and In-depth Interview were adopted to collect, compare, and analyze the data. The conclusions of this study are: 1. The characteristics of ¡§Electro-Magnetic Induction Lamps¡¨ are in conformance with energy-efficient lighting policies in Taiwan. 2. To provide the analysis result of the case companies¡¦ economic benefits after its adoption of ¡§Electro-Magnetic Induction Lamps¡¨. 3. To indicate the possible Dilemma of the lighting industry development of ¡§Electro-Magnetic Induction Lamps¡¨ and the energy-efficient lighting policies for the strategies to develop low-carbon cities in Taiwan. According to above research outcomes, three suggestions have been further proposed: 1. Users must change their concepts and habits of lighting usage in order to cultivate good energy-saving habits. 2. Users must select appropriate illumination sources according to their needs in order to achieve most effectiveness of lighting economics. 3. According to the needs of appropriate illumination sources, the government should promote and subsidize the development and use of ¡§Electro-Magnetic Induction Lamps¡¨.

The focus of this study is mono-layer polymer light emitting diode (PLED). The emitting layer is poly-p-phenylenebenzobisoxazole (PBO). PBO is a fully conjugated heterocyclic aromatic rigid-rod polymer. Anode is indium-tin-oxide (ITO). Cathode is aluminum (Al). We used UV epoxy resin to package PLED devices, then measured current-voltage response, electroluminescence (EL) emission, and device lifetime. We demonstrate that the packaged mono-layer PBO LED reduced its demise from water and oxygen. Device lifetime increased from 1 hour to several hundred hours. At a larger bias voltage or current, emission intensity and device efficiency became higher. But decay rate increased leading to shortened device lifetime. Device temperature appeared linearly with current density. A red shift of the EL emission was observed. The £fmax. of emission spectra moved from 534 nm (initial) to 582 nm (after 100 hrs). After thermal annealing at 120¢J for ten hours, threshold voltage increased from 5 V to 12 V, current density decreased to several 10 mA/cm2, luminous intensity improved several ten times to 10-2 cd/m2, emission color changed from yellow-green to orange, luminous efficiency improved from 10-7 to 10-4 cd/A, but device lifetime declined to less than 20 hrs.

The fiber-optics communication device with a plastic optical fiber (POF) has become a technology of increasing interests. The attenuation of commercial available POF has been improved to tens of decibels per kilometer. Due to its flexibility and high alignment efficiency, it has been widely used in many areas. In this study, different end shapes of POF have been proposed to increase the coupling efficiency of a POF from a surface emitting LED. Both the experiments and a ray tracing simulation are performed to investigate the coupling scheme. Experimental results also illustrate the feasibility of using ray tracing model in POF end shapes design. The effect of ball fiber lens on coupling efficiency is studied first. Lens material is EPO-TEK 353ND two parts epoxy. The result indicates that the ball fiber lens can improve the coupling efficiency significantly. A more impact end shape modified from the ball fiber lens is proposed in this study, i.e. a thin tip-rounded fiber lens. Numerical and experimental results show the tip can work as good as a ball fiber lens does. A reflection-styled end shape has also been proposed in this thesis, i.e. a taper-ended POF. In this design, the taper edge serves as a reflector to bend the rays incident on it by total internal reflection. The maximum efficiency achieves a great improvement from the previous design. Further study on the various fiber types with different sizes and numerical apertures have also been studied by the ray tracing model.