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Electrical properties modulation in spray pyrolysed Cu2SnS3 thin films through variation of copper precursor concentration for photovoltaic application
- Patel, Biren, Pati, Ranjan K., Mukhopadhyay, Indrajit, Ray, Abhijit
- Journal of analytical and applied pyrolysis 2018 v.136 pp. 35-43
- Raman spectroscopy, X-ray diffraction, absorbance, copper, electrical properties, glass, pyrolysis
- Thin film of Cu2SnS3 (CTS), a truly inexpensive photovoltaic absorber is deposited by low cost and non-vacuum spray pyrolysis technique on glass substrates. As deposited CTS films are of p-type in nature, however they are characterised with undesirably high free carrier concentration which leads to a large amount of recombination. Such a high carrier concentration is successfully reduced from 1020 cm−3 to the order of 1018 cm−3 by varying the initial molar copper concentration in the precursor solution. A combined XRD and Raman spectroscopy analysis reveals that the coexistence of secondary Cu3SnS4 phase is responsible for the higher carrier concentration of the order of 1021 cm−3, due to its semi-metallic nature. The optical study of the film also shows the reduction in the band gap from 1.73 eV to 1.29 eV with the absorption coefficient of >104 cm-1. These features of the precursor optimised CTS film enable it as a promising photovoltaic absorber.