MODELING AND SIMULATION OF NANOWIRE SOLAR CELLS

Abstract

Recently nanomaterials like Nanowire (NW), nanoparticle and quantum dot have shown to have important characteristics like lager surface to volume ratio and quantum confinement effects that can be exploited by using them as an active element in the solar cells. NW structured solar cells have shown promising potential for integrated power source for nanoelectronics systems such as driving element for nanowire sensors and logic gates. In this thesis, we report 3D-TCAD study of lateral p-type/intrinsic/n-type (p-i-n) coaxial, vertical pn and multijunction NW solar cells. We have modeled electric field inside the radial and planar structures showing advantages of radial structures. The performance of NW solar cell is benchmarked with similar dimension planar structure under same illumination conditions. The doping densities of p-core, n-shell and thickness of intrinsic shell are optimized. The effect of using low quality material on solar cell performance is also investigated. The studies shows that for a given level of defect density radial structure gives overall higher efficiency than planar structure. Our results have significant importance for design of vertical NW based solar cells and applications. We also investigated a novel NW based multifunction solar cell. This structure utilizes concept of splitting incoming energy spectrum into multiple (two for our structure) segments, each of which contribute to charge generation separately to enable more efficient charge collection. The result show enhanced efficiency of up to 20%.