Crystal structures and band-gap energies of Cu2Sn(S,Se)3 (0≤ x ≤1.0) solid solution



Cu2Sn(S1–xSex)3 (CTSSe) solid solutions with 0 ≤ x ≤ 1.0 were synthesized by mixing the elemental powders and post-annealing at 600 °C. The crystal structure of Cu2SnS3 (CTS), Cu2SnSe3 (CTSe), and their solid solution were determined by Rietveld refinement of the powder X-ray diffraction data. CTSSe solid solution had a monoclinic crystal system [space group: Cc (No. 9)]. The refined lattice parameters of CTS were a =6.654(8) Å, b =11.534(2) Å, c =6.659(4) Å, and β =109.40(5)° and those of CTSe were a =6.964(6) Å, b =12.056(6) Å, c =6.972(4) Å, and β =109.49(1)°. The lattice parameters, a, b, and c of CTSSe solid solution monotonically increased with increasing Se content. The band gap of the CTSSe solid solution linearly decreased from 0.87 eV (x=0.0) to 0.67 eV (x=0.60) with increasing Se content. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)