Electrodeposition of Cu-Zn-Sn Precursors from an Acidic Solution for Cu2ZnSnS4 Absorber Layers
Alloy deposition of Cu-Zn-Sn enables the growth of ternary alloy from a single bath solution. However, the different reduction potentials of metal ions influence the uniformity and morphology of precursor films and the stability of the solution bath . Our aim is to obtain a suitable solution bath for the electrodeposition of Cu-Zn-Sn with complexing agents and surfactants to manufacture compact, uniform and smooth ~ 1 cm2 precursors to form CZTS via sulfurization. Alloy electrodeposition was performed from an acidic solution at room temperature. Cu-Zn-Sn alloy precursor films have a suitable composition to form CZTS with atomic ratios Zn/Sn~ 1 and Cu/(Zn+Sn)~1 [Figure 1]. The electrodeposited Cu-Zn-Sn precursors were sulfurized in a quartz tube in argon atmosphere at 500-550°C for 1-2 hours. The crystal structure of the films was investigated by X-ray diffraction and Raman spectroscopy. XRD patterns after sulfurization of the precursors are shown in Figure 2. These films dominantly show peaks from the CZTS phase with a few reflections from secondary phases. Photoresponse of CZTS films was investigated in 0.1M Eu(NO3)3 solution with pH 2.3 under simulated solar light. The current-voltage plot for the CZTS film with Zn/Sn atomic ratio 1.37 is shown in Figure 3. The cathodic photocurrent increased gradually at more negative potentials, which suggests CZTS film exhibit p-type conductivity. The photocurrent produced around -0.95 V (vs. MSE) is 0.51 mA/cm2.
Figure 1 Composition of precursors as a function of deposition potential
Figure 2 XRD patterns for precursors after sulfurization at 500°C
Figure 3 J-V plot of the photocurrent response of CZTS film in 0.1M Eu(NO3)3solution
A. H. Reshak ,K. Nouneh,I. V. J. Bila, S. Auluck, H. Kamarudin, Z. Sekkat, J Electrochem Sci 9(2014) 955 - 974
W Wang, MT Winkler, O Gunawan, T Gokmen, Teodor K Todorov, Y Zhu, DB Mitzi, Adv. Energy Mater. 4 (2014) 7.
L. Guo, Y. Zhu, O. Gunawan, T. Gokmen, V. R. Deline, S.Ahmed, L. T. Romankiw, H. Deligianni, Progr.Photovolt.: Res. Appl. 22 (2014) 1.
J.-O. Jeon, K. D. Lee, L. S. Oh, S.-W. Seo, D.-K. Lee, H.Kim, J.-H. Jeong, M. J. Ko, B. Kim, H. J. Son, J. Y.Kim, Chem. Sus. Chem. 7 (2014) 4.
D. Colombara, A. Crossay,L. Vauche, A. Crossay, S. Jaime, M. Arasimowicz, P.-P. Grand, P.J. Dale, Phys Status Solidi 212(2015)1