i need semior report on si nanowire based solar cell plz send me
from
sneha

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i need seminar report on si nanowire based solar cell plz send to me
thank you
sneha

seminar report of si nanowire based solar cells

Abstract

Silicon thin films are promising optical absorber layers for inexpensive thin film solar cells that are fabricated on foreign substrates, such as glass and stainless steel. While the reported efficiencies of nanocrystalline Si based thin film solar cells have been higher than the known stabilized efficiency of amorphous silicon based thin film solar cells, they don't compare to the efficiencies reported for wafer based silicon solar cells. This is mainly due to the recombination of minority carriers at grain boundaries and intra-grain defects that are present in the nanocrystalline-Si absorber layer. Therefore, a device geometry that allows the benefits of nanostructure and also lowers grain boundary defects should greatly enhance efficiency, reduce the cost of the final solar cell and help increase market penetration. Vertically aligned silicon nanowire (SiNW) solar cells have already been shown theoretically to be much less sensitive to impurities, have low reflective losses and significantly higher optical absorption compared to planar Si Solar cells. A number of devices based on SiNW building blocks have been suggested; however, high performance and scale-up utilizing low cost processing approaches to produce effective devices remain a challenge. A high volume and large sample area catalytic chemical vapor deposition system has been designed and built to synthesize silicon nanowires using the vapor-liquid-solid growth process. The nanowires were fabricated on gold coated p-type Si substrates. The formation of nanowires was confirmed by secondary and transmission electron microscope analysis. Design of experiments was carried out to identify the SiNW process window for solar cell applications. The catalytic chemical vapor deposition at 550°C and 150 torr process pressure yield nanowire growth with higher populations. P-i-n type solar cell devices were fabricated by growing i-type SiNWs on a p-type wafer followed by forming a top emitter layer using n-ty- e spin-on-dopant. Further process optimization is on going for realizing high efficiency silicon nanowire solar cells.

Introduction

Solar cells based on nanowire (NW) array has shown promising potential for the low cost photovoltaic because of light absorption and charge carrier transport in this structure are in orthogonal direction to each other. In this study, we report the effect of variation of doping and defect densities on vertical NW solar cell bench-marked with standard planar structure using 3D-TCAD simulation. The performance of NW and planar structure for different amount of defect densities in the structures is investigated. We show that performance of NW solar cell continuously increases with wire doping. The results show that for increased efficiency, a high p-core and n-shell doping densities (~1019 cm-3) are needed. This is attributed to radial structure of NW and increased field assisted charge separation. It is found that for same amount of illuminated area, NW structure has ~25% higher conversion efficiency. Further it is found that NW radial structure can tolerate defect density as high as 1018 cm-3, with 82% higher conversion efficiency than planar structure. Our results have significant importance for design of vertical NW based solar cells and applications.