Mohamed Al-Achkar
Efficiency enhancement and degradation processes in CuxS/CdS thin film solar cells
Al-Achkar, Mohamed
Authors
Contributors
C. G. (Cyril Gordon), 1938 Scott
Supervisor
Abstract
An investigation has been made into the structure and properties of polycrystalline CuxS-CdS solar cells in order to develop an improved understanding of some of the processes which lead to unsatisfactory reproducibility and long term stability of the characteristics of these devices. The cells studied during this project were fabricated using vacuum evaporation for production of the CdS base layer and the well known chemical exchange process in a CuCl solution for formation of the CuxS layer. In view of the non-uniform thickness of the CuxS layer and non-planar structure of the Cu, S-CdS interface, it was found to be necessary to employ a variety of different characterisation techniques to monitor changes in the structure and properties of the devices. These techniques included I/V, C-V, spectral response and sheet resistance measurements, electrochemical analysis, cathodoluminescence spectroscopy and Rutherford backscattering. Detailed consideration was given to the influence of the conditions of formation on the properties of each cell component, in order to establish procedures necessary for the production of reproducible structures. particular attention was paid to the rate of growth of the CuxS layer and a theoretical analysis was developed to account for the time dependence of the growth in mean thickness of the CuxS layer in terms of the contributions associated with growth at the surface of the CdS layer and in the CdS grain boundary regions. The grain boundary contribution was found to be very sensitive to the CdS grain structure and to the previous treatment given to the CdS layer. Pre-annealing in air at 2000C enhanced the grain boundary penetration while the effect of ion implantation (with either Cu or Zn ions) was found to depend on the initial structure and the implantation conditions, but substantial improvements in the photovoltaic conversion efficiency were shown to be possible as a result of such treatment.The rate of degradation of cells exposed to air was also found to be dependent on the previous history of the cell. An increased concentration of Cd in the CuxS film (due to diffusion from the CdS layer) appeared to reduce the rate of qegradation while use of the standard stabilizing treatment (deposition of Cu overlayer followed by annealing in air) was shown to reduce interfacial diffusion as well as protecting the front surface of the CuxS layer against oxidation.
Citation
Al-Achkar, M. (1990). Efficiency enhancement and degradation processes in CuxS/CdS thin film solar cells. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4210418
Thesis Type | Thesis |
---|---|
Deposit Date | Aug 15, 2011 |
Publicly Available Date | Feb 22, 2023 |
Keywords | Solid state physics; Solar energy |
Public URL | https://hull-repository.worktribe.com/output/4210418 |
Additional Information | Department of Applied Physics, The University of Hull |
Award Date | Aug 1, 1990 |
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Copyright Statement
© 1990 Al-Achkar, Mohamed. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
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