2018 CST_CdTe_Microstructure_SolMat.pdf (1023.96 kB)

Effect of CdCl2 passivation treatment on microstructure and performance of CdSeTe/CdTe thin-film photovoltaic devices

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journal contribution
posted on 23.07.2018 by Amit Munshi, Jason M. Kephart, Ali Abbas, Adam Danielson, Guillaume Gelinas, Jean-Nicolas Beaudry, Kurt L. Barth, Michael Walls, Walajabad S. Sampath
The effects of the CdCl2passivation treatment on thin-film CdTe photovoltaic films and devices have been extensively studied. Recently, with an addition of CdSeTe layer at the front of the absorber layer, device conversion efficiencies in excess of 19% have been demonstrated. The effects of the CdCl2passivation treatment for devices using CdSeTe has not been studied previously. This is the first reported study of the effect of the treatment on the microstructure of the CdSeTe /CdTe absorber. The device efficiency is < 1% for the as-deposited device but this is dramatically increased by the CdCl2treatment. Using Scanning Transmission Electron Microscopy (STEM), we show that the CdCl2passivation of CdSeTe/CdTe films results in the removal of high densities of stacking faults, increase in grain size and reorientation of grains. The CdCl2treatment leads to grading of the absorber CdSeTe/CdTe films by diffusion of Se between the CdSeTe and CdTe regions. Chlorine decorates the CdSeTe and CdTe grain boundaries leading to their passivation. Direct evidence for these effects is presented using STEM and Energy Dispersive X-ray Analysis (EDX) on device cross-sections prepared using focused ion beam etching. The grading of the Se in the device is quantified using EDX line scans. The comparison of CdSeTe/CdTe device microstructure and composition before and after the CdCl2treatment provides insights into the important effects of the process and points the way to further improvements that can be made.

Funding

This work was partially supported by the National Science Foundation (NSF) Industry/University Collaborative Research Center (I/UCRC) under award number 1540007, National Science Foundation (NSF) PFI:AIR-RA program under award number 1538733 and U.S. Department of Energy (DOE) Small Innovative Projects in Solar (SIPS) under award number DE-EE0008177. The authors at Loughborough University are grateful to RCUK for funding through the EPSRC Supergen SuperSolar Hub (EP/J017361/1).

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Solar Energy Materials and Solar Cells

Volume

186

Pages

259 - 265

Citation

MUNSHI, A. ... et al, 2018. Effect of CdCl2 passivation treatment on microstructure and performance of CdSeTe/CdTe thin-film photovoltaic devices. Solar Energy Materials and Solar Cells, 186, pp.259-265.

Publisher

© Elsevier

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2018

Notes

This paper was accepted for publication in the journal Solar Energy Materials and Solar Cells and the definitive published version is available at https://doi.org/10.1016/j.solmat.2018.06.016.

ISSN

0927-0248

Language

en

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