Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-02T20:30:55.553Z Has data issue: false hasContentIssue false

Effect of Bandgap Grading on the Performance of a-Si1-xGex:H Single-Junction Thin-Film Solar Cells

Published online by Cambridge University Press:  23 June 2011

H. J. Hsu
Affiliation:
Department of Photonics, National Chiao Tung University, Hsinchu, Taiwan
C. M. Wang
Affiliation:
Department of Photonics, National Chiao Tung University, Hsinchu, Taiwan
C. H. Hsu
Affiliation:
Department of Photonics, National Chiao Tung University, Hsinchu, Taiwan
C. C. Tsai
Affiliation:
Department of Photonics, National Chiao Tung University, Hsinchu, Taiwan
Get access

Abstract

In this work, the effect of bandgap grading of hydrogenated amorphous silicon germanium (a-Si1-xGex:H) absorber near the p/i and the i/n interfaces was investigated. The a-Si1-xGex:H single-junction solar cells were improved by applying both p/i grading and i/n grading. Our results showed that both the p/i and the i/n grading can increase the open-circuit voltage (VOC) as compared to the cell without grading. The i/n grading can further improve the FF. Presumably the potential gradient created by the i/n grading can facilitate the hole transport thus it can improve the FF. However, the JSC decreased as the i/n grading width increased. The reduction of JSC was due to the loss in the red response, which can be attributed to the replacement of lower bandgap material by the larger ones. Combining the effects of VOC, JSC and FF, a suitable thickness of the p/i and the i/n grading was 20 nm and 45 nm, respectively. Finally, the grading structures accompanied with further optimization of doped layers were integrated to achieve a cell efficiency of 8.59 %.

Type
Research Article
Copyright
Copyright © Materials Research Society 2011

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Staebler, D. L. and Wronski, C. R., Appl. Phys. Lett. 31, 292 (1977).10.1063/1.89674Google Scholar
2. Middya, A. R., Ray, S., Jones, S. J., and Williamson, D. L., J. Appl. Phys. 78, 4966 (1995).10.1063/1.359787Google Scholar
3. Shima, M., Terakawa, A., Isomura, M., Tanaka, M., Kiyama, S., and Tsuda, S., Appl. Phys. Let. 71, 84 (1997).10.1063/1.119476Google Scholar
4. Wang, C. M., Huang, Y. T., Yen, K. H., Hsu, H. J., Hsu, C. H., Zan, H. W., and Tsai, C. C., Mat. Res. Soc. Symp. Proc. 1245, 85 (2010)10.1557/PROC-1245-A04-02Google Scholar
5. Yang, J., Banerjee, A., and Guha, S., Appl. Phys. Lett. 70, 2975 (1997).10.1063/1.118761Google Scholar
6. Zambrano, R. J., Rubinelli, F. A., Rath, J. K., and Schropp, R. E. I., J. Non-Cryst. Sol. 299, 1131 (2002).10.1016/S0022-3093(01)01080-8Google Scholar
7. Zambrano, R. J., Rubinelli, F. A., Arnoldbik, W. M., Rath, J. K., and Schropp, R. E. I., Sol. Energy Mater. Sol. Cells 81, 73 (2004).10.1016/j.solmat.2003.08.017Google Scholar
8. Zimmer, J., Stiebig, H., and Wagner, H., J. Appl. Phys. 84, 611 (1998).10.1063/1.368088Google Scholar