D. Tiwari, T.K. Chhaudhuri, T. Shripathi, U. P. Deshpande, R. Rawat, Solar Energy Materials and Solar Cells, 113 (2013) 165.
R. Jacob, R. Geethu, T. Shripathi, V. Ganesan, U. P. Deshpande, S. Tripathi, B. Pradeep, R. R. Philip, J. Inorg. Organomet. Polym. 23 (2013) 424.
The binding energy of Cu 2p1/2 and Cu 2p3/2 peaks are 953.2 and 933.4 eV, respectively. The absence of shake-up or satellite peaks around 942 eV implies the nonexistence of Cu2+ ion. The binding energies for Sn 3d5/2 and Sn 3d3/2 are 486.6 and 495.03 eV, respectively and that for S2p3/2 and S2p1/2 are 160.89 and 162.04 eV, respectively. The experimental data indicates that Cu and Sn are present in +1 and +4 oxidation states. According to the quantitative analysis, the relative concentration of Cu, Sn and S is found to be 30%, 15% and 49%, respectively. Whereas, concentration of C and O is 1% and 3%, respectively. The [Cu]/[Sn] ratio suggests slightly Cu deficient and Sn excess stoichiometry.