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A study of fabricating the first electrospun polymer-fiber solar cell with MEHPPV is presented. Motivation for the work and a brief history of solar cell is given. Limiting factors to improvement of polymer solar cell efficiency are illustrated. Electrospinning is introduced as a technique that may increase polymer solar cell efficiency, and a list of advantages in the technique applied to solar cell is discussed. Results of electrospun polymer-fiber solar cell, absorption, and its device parameter diagnosis through an equivalent circuit analysis are presented.

ITO/Si heterojunction solar cells fabricated by post annealing of ITO films were presented. The cells were obtained by first depositing ITO films at room temperature by rf magnetron sputter technique. The as-deposited film is amorphous and its sheet as low as 35 £[/¡¼ was obtained. The sheet resistance by post annealing the sample in vacuum at 300¢J 20min. reduced to 9.7 £[/¡¼. The diffraction peaks on (222) and (400) directions were observed by XRD analysis. In addition, the carrier concentration is increased from 3¡Ñ1020 cm-3 to 9¡Ñ1020cm-3. The average transmittance is 82% after annealing. The ideality factor of the heterojunction diode is 1.93. We believed that the performance of the ITO/Si cells is limited due to large series resistance and carrier recombination at interface.

The dominant research subjects are focused on the growth of high quality stoichiometric undoped CuInSe2 epitaxial films by molecular beam epitaxial growth. For MBE growth, it is possible to obtain the high quality epitaxial films and to get the reproducibility and stability of the composition and properties of epilayers by controlling the growth parameters carefully. Under the conditions of fixed Cu molecular beam flux and excess Se molecular beam flux, we can control the In/Cu compositon ratio by changing In molecular beam flux to get stoichiometric and In-rich or Cu-rich epitaxial films. We hope it can be used in the manufacture of solar cell and get high conversion efficiency.

The dominant research subjects are focused on the growth of high quality stoichiometric of CuInSe2 epitaxial films by chemical electrodeposited. For chemical electrodeposited growth, it is possible to obtain the high economical films and to get easier and quicker of the composition and properties by controlling the growth parameters carefully. Under the conditions of fixed copper ion¡]Cu2+¡^concentration and excess indium ion¡]In3+¡^concentration, we can change selenium¡]Se4+¡^ concentration to get films. We hope it could be used in the manufacture of solar cell and get high conversion efficiency.

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One way of reducing the cost of crystalline silicon solar cell fabrication is by increasing the conversion efficiency of the device. However, most high efficiency solar cell designs require more complex fabrication methods that also increase the fabrication cost. Photolithography is an example of such an indispensable but costly process. The most common use for photolithography in solar cell fabrication is for dielectric patterning. In this thesis, inkjet printing is proposed as an alternative method for dielectric patterning in solar cell fabrication. There are two inkjet printing methods developed in this thesis. The indirect inkjet patterning method involves the deposition of a suitable plasticiser droplet onto an intermediate resin coating layer on top of the dielectric surface. Diethylene glycol and novolac resin are used as the plasticiser and coating layer respectively. The plasticiser changes the permeability of the affected region of the resin such that it becomes permeable to liquid dielectric etchants. When the resin layer is removed, the printed pattern is transferred to the dielectric layer. The optimised process produces round openings with diameters as small as 30-35 μm and continuous line patterns with width as narrow as 40-50 μm. The direct inkjet patterning method involves the deposition of liquid phosphorus dopant sources onto both silicon and dielectric surfaces. Two types of phosphorus sources are used: phosphoric acid and specially-formulated dopant sources. Narrow lines as wide as 15-20 μm are produced after appropriate surface treatments on both silicon and dielectric surfaces. Using this method, a process that simultaneously pattern the dielectric layer and diffuse the silicon underneath is developed. Various high efficiency solar cell structures such as selective emitter, localised contacts, surface texturing and edge isolation are demonstrated using the indirect inkjet patterning method. Both inkjet patterning methods are then used in the fabrication of a selective emitter solar cell. Fill factors in the range of 0.79-0.80 are shown to be achievable with both patterning methods, thus indicating the high quality metal-silicon contacts formed by these inkjet techniques.

The experiment divided into two parts. One is silicon solar cell process. The other is InGaN solar cell process. Borosilicafilm solution spin onto the n-type silicon (111) substrate and spread through the high-temperature furnace tube to form a p-n junction silicon solar cell. Then, evaporate top and rear contact by electron beam evaporation system. InGaN p-i-n structure solar cell grows on sapphire substrate by plasma-assisted molecular beam epitaxy system (PA-MBE) and its process is by repeated photolithography, inductive coupled plasma etching and wet etching. In the device fabrication process, the first is defining the sample size(mesa). Second, etched to the n-type GaN layer, and then coated metal as electrode. Finally, we get the device. In the measurement, the measurement of I-V curve of samples in the light by solar simulator of AM1.5 G light source observe open circuit voltage, short circuit current, fill factor, and efficiency. In addition, we measure the external quantum efficiency of the samples by IPCE and observe the photoelectric conversion efficiency of samples at different wavelength. Observed the sample quality and the indium composition of InGaN layer by XRD. We observe the InGaN band gap shift by variable-temperature photoluminescence spectra.

Excitonic photovoltaic devices, including organic, hybrid organic/inorganic, and dye-sensitized solar cells, are attractive alternatives to conventional inorganic solar cells due to their potential for low cost and low temperature solution-based processing on flexible substrates in large scale. Though encouraging, they are currently limited by the efficiency from not yet optimized structural and material parameters and poor overall knowledge regarding the fundamental details. This dissertation aims to achieve improved performance of hybrid solar cells by enhancing material property and designing new device architecture. The study begins with the addition of XD-grade single-walled carbon nanotube (XDSWNT) into poly(3-hexylthiophene) (P3HT) to improve the current density. By having a weight ratio of XDSWNT and P3HT equaled to 0.1:1, short-circuit current was quadrupled from 0.12 mA cm-2 to 0.48 mA cm-2 and solar cell efficiency was tripled from 0.023% to 0.07%, compared to devices with pure P3HT as a hole transport material. Secondly, a significant improvement in device efficiency with 250 nm long ZnO nanorod arrays as photoanodes has been achieved by filling the interstitial voids of the nanorod arrays with ZnO nanoparticles. The overall power conversion efficiency increased from 0.13% for a nanorod-only device to 0.34% for a device with combined nanoparticles and nanorod arrays. The higher device efficiency in solid-state DSSCs with hybrid nanorod/nanoparticle photoanodes is originated from both large surface area provided by nanoparticles for dye adsorption and efficient charge transport provided by the nanorod arrays to reduce the recombinations of photogenerated carriers. Followed by the novel layer-by-layer self-assembly deposition process, the hybrid photoanode study was extended to the longer ZnO nanorod arrays. The best performance, 0.64%, was achieved when the thickness of the photoanodes equaled to 1.2 ?m. Finally, the photovoltaic devices were modified by adding ZnO nanoarpticles into P3HT to increase interfacial area between ZnO and P3HT. The efficiency was enhanced from 0.18% to 0.45% when the ZnO nanorod arrays were 625 nm in length. Our successful design of the device morphology significantly contributes to the performance of solid-state hybrid solar cells.