Investigation of combinatorial coevaporated thin film Cu{sub 2}ZnSnS{sub 4}. I. Temperature effect, crystalline phases, morphology, and photoluminescence
- National Renewable Energy Laboratory, 15013 Denver West Parkway, MS3218, Golden, Colorado 80401 (United States)
- Renishaw Incorporated, 5277 Trillium Blvd., Hoffman Estates, Illinois 60192 (United States)
- Departments of Chemical Engineering, Electrical and Computer Engineering, and Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)
Cu{sub 2}ZnSnS{sub 4} is a promising low-cost, nontoxic, earth-abundant absorber material for thin-film solar cell applications. In this study, combinatorial coevaporation was used to synthesize individual thin-film samples spanning a wide range of compositions at low (325 °C) and high (475 °C) temperatures. Film composition, grain morphology, crystalline-phase and photo-excitation information have been characterized by x-ray fluorescence, scanning electron microscopy, x-ray diffraction, Raman spectroscopy, and photoluminescence imaging and mapping. Highly textured columnar grain morphology is observed for film compositions along the ZnS-Cu{sub 2}ZnSnS{sub 4}-Cu{sub 2}SnS{sub 3} tie line in the quasi-ternary Cu{sub 2}S-ZnS-SnS{sub 2} phase system, and this effect is attributed to structural similarity between the Cu{sub 2}ZnSnS{sub 4}, Cu{sub 2}SnS{sub 3}, and ZnS crystalline phases. At 475 °C growth temperature, Sn-S phases cannot condense because of their high vapor pressures. As a result, regions that received excess Sn flux during growth produced compositions falling along the ZnS-Cu{sub 2}ZnSnS{sub 4}-Cu{sub 2}SnS{sub 3} tie line. Room-temperature photoluminescence imaging reveals a strong correlation for these samples between film composition and photoluminescence intensity, where film regions with Cu/Sn ratios greater than ∼2 show strong photoluminescence intensity, in comparison with much weaker photoluminescence in regions that received excess Sn flux during growth or subsequent processing. The observed photoluminescence quenching in regions that received excess Sn flux is attributed to the effects of Sn-related native point defects in Cu{sub 2}ZnSnS{sub 4} on non-radiative recombination processes. Implications for processing and performance of Cu{sub 2}ZnSnS{sub 4} solar cells are discussed.
- OSTI ID:
- 22273463
- Journal Information:
- Journal of Applied Physics, Vol. 115, Issue 17; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COPPER SULFIDES
EXCITATION
FLUORESCENCE
MORPHOLOGY
PHOTOLUMINESCENCE
POINT DEFECTS
RAMAN SPECTROSCOPY
SCANNING ELECTRON MICROSCOPY
SOLAR CELLS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEXTURE
THIN FILMS
TIN SULFIDES
X-RAY DIFFRACTION
ZINC SULFIDES