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.

This thesis focuses on development of novel nanomaterials, including semiconductor quantum dots (QDs) and gold nanoparticles (AuNPs), for fabricating white-light emitting devices and assaying thiols in biological and environmental samples. The thesis mainly contains two divisions. One demonstrates synthesis, optical properties and white-light emissions of alloyed quantum dots and their application to light-emitting devices. The other describes to combine functionalized gold nanoparticles with capillary electrophoresis and accomplish high selectivity and ultrasensitive detection for thiols. First, through one-step aqueous synthesis, alloyed ZnxCd1¡VxSe QDs have been successfully prepared at low temperatures by reacting a mixture of Cd(ClO4)2 and Zn(ClO4)2 with NaHSe using 3-mercaptopropionic acid as a surface-stabilizing agent. The optical properties and composition of the alloyed QDs were highly dependent on the molar ratio of Zn2+ to Cd2+. With the increase in Zn content, a systematic blue shift occurred in the first exciton absorption and band edge emission. Moreover, X-ray diffraction peaks of the alloyed QDs systematically shifted to larger angles simultaneously. These systematic shifts indicated the formation of the alloyed QDs. Interestingly, among these alloyed QDs, Zn0.93Cd0.07Se QDs exhibited white-light emission with quantum yields of 12%. In addition, we discovered that we could adjust the relative strength of the band edge and trap state emissions by controlling the reaction time, thereby attain white-light-emitting QDs. Finally, we blended alloyed QDs with ultraviolet-transparent polydimethylsiloxane (PDMS) to develop a white-light, solid-state lighting device by using a 365-nm UV lamp as the pump source. In the other part of this thesis, we proposed a method for selective enrichment of thiols using Tween 20-capped gold nanoparticles (AuNPs) prior to capillary electrophoresis coupled with laser-induced fluorescence (CE-LIF). By forming Au-S bonds, Tween 20-AuNPs can selectively extract thiols from a complicated matrix. A Tween 20 capping layer not only suppresses nonspecific adsorption, but also enables NPs to disperse in a highly-salinity solution. For analyses of aminothiols, after extraction and centrifugation, thioglycollic acid was utilized to remove aminothiols that attached to the NP surfaces. The extracted aminothiols was derivatized with o-phthalaldehyde (OPA) followed by CE-LIF. The use of this nanoprobe provided approximately 11-, 282-, and 21-fold sensitivity improvements for homocysteine (HCys), glutathione (GSH), and £^-glutamylcysteine (GluCys), respectively. Furthermore, the limits of detection (LODs) at a signal-to-noise ratio of 3 for HCys, GSH, and GluCys are 4013, 80, and 383 pM, respectively. A practical analysis of aminothiols in human urine sample has been accomplished by our proposed method. For another application to determining thiol-containing peptides, we use dithiothreitol to remove thiol-containing peptides from the NP surface through ligand exchange. The released peptides are selectively derivatized with OPA to form tricyclic isoindole derivatives. After injecting a large sample volume, the sensitivity of these peptides was improved by stacking them via using polyethylene oxide (PEO) as additive for on-line concentration and separation. As a result, LODs for GSH, GluCys, and phytochelatins (PC2 ~ PC4) were down to 0.1-6 pM. The proposed method has the lowest LODs for five peptides compared to other reported methods, and it also detect dissolve thiols in seawater in practice. Our proposed method is capable of ultrasensitive detection for thiols in biological and environmental samples.

In the study, conductive distributed Bragg reflectors (DBRs) fabricated at room temperature based on porous indium tin oxide (ITO) on dense ITO bilayers were proposed for resonant cavity organic light emitting diodes (RCOLEDs). In the fabrication of the ITO DBRs, the low refractive index porous ITO films were obtained by applying supercritical CO2 treatment at different temperature and pressures on the spin-coated sol-gel ITO films. On the other hand, the high refractive index ITO films were grown at room temperature by long-throw reactive ratio-frequency magnetron sputtering. The refractive index of the porous ITO film and ITO films were 1.54 and 2.0, respectively. For the DBR with 4 pairs ITO bilayers, the optical reflectance of more than 70 % was achieved. The stop band and the average resistivity is 140 nm and 2.2¡Ñ10-3 £[-cm, respectively. Finally, electrical and optical characteristics of the RCOLEDs fabricated on the ITO DBR were investigated and compared with those of the conventional OLEDs. The maximum luminous efficiency of 3.79 cd/A was obtained at 347 mA/cm2 for the RCOLED. This luminous efficiency was 26 % higher than that of the conventional OLED.

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.

In this research, the contents are divided into two sections. In the first section, we investigated carrier transport behavior of organic optoelectronic devices by using space charge limited current(SCLC) method. Firstly, we fabricated a hole-only device (ITO/Spiro-MeOTAD/Al) for Sprio-MeOTAD and the current density¡V voltage(J-V) characteristics of the device was measured. The J-V characteristics of the device do not match with SCLCs very well at high voltage since the number of hole injection was not enough to achieve SCLCs condition. To enhance the injection of hole carrier into the organic layer, a MoO3 buffer layer was inserted between ITO electrode and organic layer. The current density in device with MoO3 buffer layer achieved 5 times enhancement, indicating that the concentration of hole in MoO3 device is increment. Hence, we succeeded in making the J-V characteristics of the hole-only device to match with SCLCs well at high voltage, and the hole mobility of Sprio-MeOTAD estimated by SCLCs was 1.44¡Ñ10-4cm2/Vs. Li salt was also doped into Sprio-MeOTAD as an n-type dopant. We found that Li salt could form hole-traps in Sprio-MeOTAD, which reduced hole carriers in Spiro-MeOTAD. The current density of the device was decreased, and the device could not achieve SCLCs condition at high voltage. In the second section, we use two novel iridium(Ir) complexes to fabricate blue-green emitting devices by solution process. First, we obtained optimum concentration of phosphorescent emitters by controlling of the dopants concentration. Then, we adjusted the thickness of the electron injection layer, hole injection layer, and emission layer to design more suitable device structure. Finally, we succeeded in fabricating blue-green light emitting devices. The maxima luminescence was 37.7cd/m2 and maxima current efficiency was 1.68 cd/A in the Ir complex based devices.

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¡¨.

Opto-electronics of non-fully conjugated molecules was demonstrated successfully in this research as light emitting diodes (LEDs). A series of benzoxazole poly[2,2-(m-2-hydroxyl phenylene)-4-4¡¦-hexafluoroisopro- pane-bibenzoxazoles] (6F-PBO-OH, Am) and benzimidazole poly[2,2¡¦- (2-hydroxy-o-phenylene)-5,5¡¦-bibenzimiazole] (OH-Pbi, B(1-m)) were copolymerized for coil-like non-fully conjugated poly-(Am-co-B(1-m)) for luminescence investigation. UV-Vis absorption of the non-fully conjugated copolymers showed superposition of individual absorption response from the two chemical components of the copolymer. However, the photoluminescence (PL) and the electroluminescence (EL) emissions had a red shift with increasing OH-Pbi content. It seemed to suggest that OH-Pbi was more charge delocalized than 6F-PBO-OH. In mono-layer LEDs, the diode threshold voltages were about at 2 ~ 3 V and the EL showed a green emission. Tunable emission was not observed in varying the m value of the copolymers. Composites of copolymer, poly(Am-co-B(1-m)) and multi-wall carbon nanotube (MWNT) were in-situ synthesized for mono-layer LED fabrication. Few MWNT aggregation was observed via the field-emission scanning electron microscopy. It was a success in dispersing MWNT in the copolymers. There was a red shift with MWNT addition in the PL and the EL emissions. The diode threshold voltages were about at 2 ~ 5 V and the EL emission still showed a green emission. According to this study, MWNT was inconsequential on the PL and the EL emissions of the copolymers up to 2 wt. %.