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Journal Article
Photovoltaic Performance and Interface Behaviors of Cu(In,Ga)Se2 Solar Cells with a Sputtered-Zn(O,S) Buffer Layer by High-Temperature Annealing
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- Authors
- Jae-Hyung Wi, Tae Gun Kim, Jeong Won Kim, Woo-Jung Lee, Dae-Hyung Cho, Won Seok Han, Yong-Duck Chung
- Issue Date
- 2015-07
- Citation
- ACS Applied Materials & Interfaces, v.7, no.31, pp.17425-17432
- ISSN
- 1944-8244
- Publisher
- American Chemical Society(ACS)
- Language
- English
- Type
- Journal Article
- Abstract
- We selected a sputtered-Zn(O,S) film as a buffer material and fabricated a Cu(In,Ga)Se2 (CIGS) solar cell for use in monolithic tandem solar cells. A thermally stable buffer layer was required because it should withstand heat treatment during processing of top cell. Postannealing treatment was performed on a CIGS solar cell in vacuum at temperatures from 300-500 °C to examine its thermal stability. Serious device degradation particularly in VOC was observed, which was due to the diffusion of thermally activated constituent elements. The elements In and Ga tend to out-diffuse to the top surface of the CIGS, while Zn diffuses into the interface of Zn(O,S)/CIGS. Such rearrangement of atomic fractions modifies the local energy band gap and band alignment at the interface. The notch-shape induced at the interface after postannealing could function as an electrical trap during electron transport, which would result in the reduction of solar cell efficiency.
- KSP Keywords
- Buffer material, CIGS solar cell, Electron transport, Energy band gap, Heat Treatment, High-temperature annealing, Local energy, Solar cell efficiency, Thermally stable, band alignment, buffer layer