Preparation of Narrow Band-Gap Cu_2Sn(S,Se)_3 and Fabrication of Film by Non-Vacuum Process

摘要

We successfully prepared a Cu_2Sn(S_(1-x)Se_x)_3 (CTSSe) solid solution with 0 ≤ x ≤ 1.0. CTSSe solid solution powders were synthesized by mixing the elemental powders and post-annealing at 600 ℃. The crystal structure of Cu_2SnS_3 (CTS) was characterized by Rietveld refinement of the powder X-ray diffraction data and determined to be a monoclinic crystal system. The band gaps of CTSSe solid solution were determined by the diffuse reflectance spectra of the powder samples and the transmittance spectrum of the film fabricated by a non-vacuum thin-film fabrication process called printing and high-pressure sintering (PHS). The band gap (E_g) of CTS is 0.87 eV, which is in good agreement with the recently reported value of monoclinic CTS film. The band gap of the Cu_2Sn(S_(1-x)Se_x)_3 solid solution linearly decreases from 0.87 eV (x = 0.0) to 0.67 eV (x = 0.6) with increasing Se content. The CTSSe solid solution has potential as a narrow band-gap absorber material for thin-film full spectrum solar cells.