Methods of enhancement of light trapping for thin film PV applications

  • Farsad Imtiaz Chowdhury

Student thesis: Master's Thesis

Abstract

In a thin film solar cell, the transparent conducting oxide (TCO) plays an important role in improving the overall efficiency of the solar cell. TCO has good electrical conductivity and high optical transparency in the operating spectrum of the cell (mainly visible and near infra-red). At present In2O3:SnO2 (ITO), ZnO:Al (AZO), SnO2:F (FTO) are the most commonly used TCOs because of their near optimum electrical and optical properties. The optical performance of TCO can be enhanced by texturing or patterning the surface. The reflectance of a smooth surface is higher than that of a textured one. The best efficiency from a solar cell can be obtained if we ensure that maximum amount of light passes through the TCO that in turn will generate maximum electron-hole pairs and allows for an enhanced current collection to be carried to the metal electrodes. In this work, we have optimized the front TCO + Glass structure in regard of the pattern to be used as well as the geometrical dimensions involved. We have established a baseline simulation process using a flat layer of TCO under glass, various materials were also explored. We investigated various structuring patterns, with a focus on experimentally implementable solutions. The software package Sentaurus TCAD from Synopsis has been used in our simulations. Ray tracing approach is used in this case to estimate the overall transmittance of different types of structures. It is found that a significant improvement of the overall transmittance compared to a flat structure can be obtained by the pyramidal structure. A set of experiments consisting of wet and dry etching has been carried in order to implement the features devised from our simulations. In addition to being able to implement some of the simulated patterns in a reliable way, we have shown that the relative gain obtained in transmittance from flat to structured sample matches the simulations.
Date of Award2013
Original languageAmerican English
SupervisorAdel Gougam (Supervisor)

Keywords

  • Materials science. Materials Science and Engineering

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