<p>A new type of flexible silicon solar cell has been fabricated by interconnecting solar cell die on a flexible substrate. The fabrication process is described in this thesis. The solar cell die were diced using two methods. One method was to dice a solar cell completely through. The other method was to dice a solar cell from its back partially and then cleave through. To study the effects of different dicing methods on the performance of solar cell die, storage delay time measurement was employed to determine the lifetime of excess electrons in the p region of the two types of solar cell die. A laser beam induced current (LBIC) scanning technique was employed to study the electrical performance of the two types of solar cell die. The carrier diffusion lengths of two types of solar cell die were also determined by traveling light spot diffusion length measurement.</p><p>The theoretical response of a solar cell was compared to experimental results at various incident light angles. OpticLab software was used to model the incident light angle and lens spacing dependence of solar cell performance.</p> / Thesis / Master of Applied Science (MASc)

This research comprehensively reviews the properties of regular micro and nano structures fabricated by laser interference lithography and reports on their applications in the antireflection and self‐cleaning surface. The research systematically investigates the laser interference lithography technology taking into account its advantages and abilities to realize various potential applications. Multiple‐beam interference lithography systems are constructed. Laser interference interaction with silicon wafer is analysed and the optical and hydrophobic properties are obtained via measurements. In order to fabricate the extremely low reflection and very large contact angle for solar cells, fabrication methods of antireflection and self‐cleaning are surveyed and their advantages and disadvantages compared. The research investigates the effect of heat transfer and the radiation of laser interference plasma on silicon wafer surfaces and proposes equations of heat flow and radiation effects of laser plasma of interfering patterns in a four‐beam laser interference distribution. Following the irradiation, the silicon wafer surface is covered with a periodic array of micrometer and nanometer‐sized structures, which have the shape of grating, cone and hole. The research also investigates the effect of different laser parameters on the optical and hydrophobic properties of the structured silicon wafer surface. The results of periodic hexagonally‐distributed hole structures fabricated by three‐beam laser interference reveals excellent design guidelines for obtaining an extremely low solar‐weighted reflection, (SWR, 1.86%) and relatively large contact angle (140°) which can provide a strong self‐cleaning capability on the solar cell surface. In addition, the research creates a novel dual structure with antireflection and superhydrophobic properties fabricated by three‐beam laser interference lithography. The fabrication method is three‐beam laser interference combined with focused laser processing interacting on the silicon wafer surface. This kind of structure has a very low SWR (3.6 %) and extremely large contact angle which is more than 150° in the wavelength range from 380 nm to 780 nm. The research shows that the laser interference lithography technology can be employed and further developed to fabricate micro and nano structures of strong antireflection and self‐cleaning functions for applications in solar cells.

The topic of this thesis is solar pump Neodymium doped Yttrium Aluminum Garnet laser, the research of characteristics is that natural sunlight is used as pumped source in instead of diode laser, pulsed Xenon lamp, Krypton arc lamp¡Ketc. In order to reduce use of electric power. By using solar concentrator system, concentration is reached to 8.89 ¡Ñ (10^10). This ratio is set to end pump Neodymium doped YAG. The output power is up to 17.54mW, and the laser slope efficiency is up to 0.04% . On application, If lasers are needed in remote locations where sunlight is abundant and other forms of energy are scarce, a solar laser would seem to be a natural choice.

Wireless backhaul communication and power transfer can make the deployment of outdoor small cells (SCs) more cost effective; thus, their rapid densification can be enabled. For the first time, solar cells can be leveraged for the two-fold function of energy harvesting (EH) and high speed optical wireless communication. In this thesis, two complementary concepts for power provision to SCs are researched using solar cells – the optical wireless power transfer (OWPT) in the nighttime and solar EH during daytime. A harvested power of 1W is considered to be required for an autonomous SC operation. The conditions of darkness – worst case scenario – are initially selected, because the SC needs to harvest power in the absence of ambient light. The best case scenario of daytime SC EH from sunlight is then explored to determine the required battery size and the additional power from optical sources. As a first approach, an indoor 5m experimental link is created using a white light-emitting diode for OWPT to an amorphous silicon (Si) solar panel. Despite the use of a large mirror for collimation, the harvested power and energy efficiency of the link are measured to be only 18:3mW and 0:1%, respectively. Up to five red laser diodes (LDs) with lenses and crystalline Si (c-Si) cells are used in a follow-up study to increase the link efficiency. A maximum power efficiency of 3:2% is measured for a link comprising two LDs and a mono-c-Si cell, and the efficiency of all of its components is determined. Also, the laser system is shown to achieve an improvement of the energy efficiency by 2:7 times compared with a state-of-the-art inductive power transfer system with dipole coils. Since the harvested power is only 25:7mW, an analytical model for an elliptical Gaussian beam is developed to determine the required number of LDs for harvesting 1W; this shows an estimated number of 61 red LDs with 50mW of output optical power per device. However, a beam enclosure of the developed Class 3B laser system of up to a 3:6m distance is required for eye safety. A simulation study is conducted in Zemax for the design of an outdoor 100m infrared wireless link able to harvest 1W under clear weather conditions. Harvesting 1:2W and meeting eye safety regulations for Class 1 are shown to be feasible by a 1550 nm laser link. The required number of laser power converters is estimated to be 47 with an area of 5 5mm2 per device. Also, the dimensions of the transmitter and receiver are considered to be acceptable for the practical application of SC EH. In the last part of this thesis, two multi-c-Si solar panels are initially used for EH in an outdoor environment during daytime. The power supply of at least 1W is shown to be achievable during hour periods under sunny and cloudy conditions. A maximum average power of 4:1W is measured in the partial presence of clouds using a 10W solar panel. Since the variability of weather conditions induces the harvested power to fluctuate with values of mW, the use of optical sources is required in periods of insufficient solar EH for SCs. Therefore, a hybrid solar/laser based EH design is proposed for a continuous annual SC provision of 1Win ‘darker’ places on earth such as Edinburgh, UK. The 10W multi-c-Si solar panel and the 1550 nm laser link are considered; thus, the feasibility of supplying the SC with at least 1Wper hour monthly using a battery with energy content of only 60Wh is shown through simulations. A maximum monthly average harvested power of 824mW is shown to be required by the 1550 nm laser system that has already been overachieved through simulations in Zemax.