Electrical and photovoltaic characteristics of CuInSe 2 thin films processed by nontoxic Cu-In precursor solutions

Author： Ik Jin Choi Jin Woo Jang Seung Min Lee Deuk Ho Yeon Yeon Hwa Jo Myung Ho Lee Jae Ho Yun Kyung Hoon Yoon Yong Soo Cho

Publisher： IOP Publishing

ISSN： 0022-3727

Source： Journal of Physics D: Applied Physics, Vol.46, Iss.24, 2013-06, pp. : 245102-245106

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Abstract

Nontoxic Cu-In solution-processed CuInSe₂ absorber thin films and resultant photovoltaic cells have been investigated. Acetate-based Cu-In precursors having different Cu/In ratios of 0.8-1.2 were deposited by spin-coating and then selenized in Se atmosphere up to 550 °C. Single tetragonal CuInSe₂ phase was dominantly obtained regardless of Cu/In ratios, with the segregation of Cu_2−xSe secondary phase only in the case of Cu-rich films as evidenced by Raman spectra. The films with the 1.1 ratio demonstrated a larger grain size of ∼1.06 µm with an increased carrier concentration of ∼1.7 × 10¹⁸ cm⁻³ and a decreased band gap of ∼1.02 eV, compared to the values obtained for Cu-deficient absorber films. The resultant best cell efficiency was ∼3.1% for the absorber having the 1.1 ratio, suggesting a potential of this simple spin-coating method as an alternative to typical vacuum processes.