Optical modeling and characterization of transparent conductive oxides

Implementation of thin film solar cells

Master thesis (2023)

Authors

L. Hendrix Applied Sciences

Contributors

A.H.M. Smets Photovoltaic Materials and Devices - EEMCS (mentor)
R. Santbergen Photovoltaic Materials and Devices - EEMCS (mentor)
F.S. Saitta Photovoltaic Materials and Devices - EEMCS (mentor)
T.J. Savenije ChemE/Opto-electronic Materials - AS (graduation committee member)
S.W.H. Eijt RST/Fundamental Aspects of Materials and Energy - AS (graduation committee member)
P. Perez Rodriguez Photovoltaic Materials and Devices - EEMCS (graduation committee member)
Faculty
Applied Sciences, Applied Sciences
Copyright: © 2023 Lorena Hendrix
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Published Date

26-04-2023

Language

English

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Faculty

Applied Sciences

Abstract

To make silicon thin film solar cells attractive to the market, their efficiencies should reach the efficiencies of the dominant crystalline silicon solar cell. Therefore the search for ways to improve the efficiency of silicon thin film solar cells continues. TCO front contact layers and back reflector layers play a significant role in the increase of thin film solar cell efficiencies. For the optical characterization of these TCO layers, commonly used methods are found to differ significantly in results regarding the extinction coefficient which makes their accuracy questionable.

This research consists of two main parts. For the first part, the commonly used optical characterization methods spectroscopic ellipsometry and spectrophotometry + data analysis in SCOUT are analyzed in accuracy and compared to newly introduced methods using spectrophotometry + data analysis in GenPro4 and photothermal deflection spectroscopy + data analysis in GenPro4 to build a guide on optical characterization of TCO materials. For the second part, the optical response determined using the software GenPro4 of a double junction silicon thin film solar cell for a novel bi-layer front contact design consisting of IOH and i-ZnO will be compared to the optical response for standard used AZO, and ITO single layers to find the best front contact design. Furthermore, the optical response of a double junction silicon thin film solar cell for a back reflector containing an i-ZnO layer on top of the silver back contact will be compared to the optical response for a back reflector containing an AZO layer on top of the silver back contact to find the best back reflector design.

From the results of the optical characterization methods, it is concluded that photothermal deflection spectroscopy + data analysis in GenPro4 is the most accurate method for determining the extinction coefficient of a TCO material. The results of the optical simulations for front contact TCO and back reflector TCO designs showed that the bi-layer can enhance the optical response of a double junction silicon thin film solar cell significantly compared to the AZO and ITO single layers. The i-ZnO TCO back reflector layer was found to induce less parasitic absorption and therefore a better optical response of the double junction silicon thin film solar cell.