Study of Light Management Schemes for Efficiency Enhancement in Thin-Film Photovoltaic Cells

  • Henrik Melkonyan

Student thesis: Master's Thesis

Abstract

Amorphous silicon (a-Si) based thin-film solar cells (TFSC) are highly promising in the PV industry due to their low production cost. One of the drawbacks is their low efficiency, when compared to crystalline silicon (c-Si). This is due to the large bandgap of a-Si, which limits the solar radiation absorption in the infrared. One of the viable solutions for the efficiency improvement consists in the design of novel light management schemes, where light absorption inside the device is enhanced. This thesis presents a study on the development of light management schemes to enhance the performance of a-Si based TFSC. In this work, light management schemes are proposed for the air/silica and silica/TCO (Transparent Conductive Oxide) interfaces. In order to optimize the light trapping performance, two dimensional transmission and reflection finite-difference time-domain (FDTD) simulations of the surface textures are compared with those of flat interfaces. Numerical results for the air/silica interface demonstrate a reduction in the reflection to values below 1%, compared to up to 4% for the non-textured interface. For the silica/TCO interface, reflection decreases to less than half when compared to the nontextured interface. Additionally, a study on the benefits of light management techniques using metallic back reflectors is carried out. The FDTD simulations demonstrate reflectance gain of up to 10% and 1%, in case of aluminum and silver back reflectors, respectively. Further investigation into the application of GRIN-like dielectric slab lenses on solar cells (standard and concentrated) has been carried out. The focusing structure can be described as a thin dielectric slab with sub-wavelength index engineering, formed by air gaps (or filled with a different refractive index material) of identical sizes. The concentration of the number of gaps varies radially and makes the dielectric slab a smoothly graded-index media, which gives it focusing or diverging properties.
Date of AwardJun 2013
Original languageAmerican English
SupervisorMarcus Dahlem (Supervisor)

Keywords

  • Thin-Film; Photovoltaic Cells; Finite-Difference Time-Domain (FDTD).

Cite this

'