Challenges and Prospects for Developing CdS/CdTe Substrate Solar Cells on Mo foils

Williams, Ben, Major, Jonathan, Bowen, Leon, Phillips, Laurie, Zoppi, Guillaume, Forbes, Ian and Durose, Ken (2014) Challenges and Prospects for Developing CdS/CdTe Substrate Solar Cells on Mo foils. Solar Energy Materials and Solar Cells, 124. pp. 31-38. ISSN 0927-0248

[img]
Preview
PDF
Zoppi_challenges_and_prospects.pdf - Published Version
Available under License Creative Commons Attribution Non-commercial No Derivatives.

Download (1MB) | Preview
Official URL: http://dx.doi.org/10.1016/j.solmat.2014.01.017

Abstract

ITO/ZnO/CdS/CdTe/Mo solar cells have been grown in the substrate configuration by a combination of close-space sublimation and RF sputtering. A peak efficiency of 8.01% was achieved. A two stage CdCl2 annealing process was developed, with the first stage contributing to CdTe doping and the second being linked to CdTe/CdS interdiffusion by secondary ion mass spectrometry analysis. The inclusion of a ZnO layer between CdS and ITO layers improved performance significantly (from η=6% to η=8%) by increasing the shunt resistance, RSH, from 563 Ω cm2 to 881 Ω cm2. Cross-sectional scanning electron microscopy highlighted the importance of the resistive ZnO layer as numerous pinholes and voids exist in the CdS film. Solar cell performance was also investigated as a function of CdTe thickness, with optimal thicknesses being in the range 3–6 μm. All devices were deemed to be limited principally by a non-Ohmic back contact, the Schottky barrier height being determined to be 0.51 eV by temperature dependent J–V measurements. Modelling of device performance using SCAPS predicted efficiencies as high as 11.3% may be obtainable upon formation of an Ohmic back-contact. SCAPS modelling also demonstrated that a quasi-Ohmic back-contact may be achievable via inclusion of a highly p-doped (~1018 cm−3) buffer layer, between CdTe and Mo, which also has an optimal electron affinity (4.2 eV). The evaluation of device processing and the in-depth characterisation presented here provides a number of insights towards the continued improvement of substrate cell performance.

Item Type: Article
Additional Information: Open Access funded by Engineering and Physical Sciences Research Council available under Creative Commons Licence - http://creativecommons.org/licenses/by-nc-nd/3.0/
Uncontrolled Keywords: CdTe, substrate, thin-film, optimisation, interdiffusion, back contact
Subjects: F200 Materials Science
F300 Physics
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Guillaume Zoppi
Date Deposited: 18 Feb 2014 08:27
Last Modified: 25 Oct 2017 20:38
URI: http://nrl.northumbria.ac.uk/id/eprint/15547

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year

View more statistics


Policies: NRL Policies | NRL University Deposit Policy | NRL Deposit Licence