Among the different ternary sulfides, Cu2SnS3 (CTS) is one of the most relevant compound for solar cell applications due to its high light absorption coefficient
(> 104 cm–1) and appropriate band–gap energy values between 0.93 and 1.35 eV dependent on the different crystal structure of the polymorphic compound. Different methods have been reported for the synthesis of CTS, such as conventional solid-state reaction [1] and solvothermal process [2], mainly for powder preparation, whereas thin films have been deposited by spray pyrolysis technique [3], and also from direct sulfurization of sputter deposited [4] or electrodeposited [5] metal precursors.
Electrodepostion (ED) has a strong interest because of its relatively easy scalability to industrial processes and its potential for reduction of costs in relation to vacuum based technologies.
In this communication, we report the preparation and characterization of ternary CTS thin films using a sequential ED of Cu and Sn metallic layers onto Glass/Mo substrates in different deposition sequences and number of sublayers ((Cu/Sn)k and (Sn/Cu)k, k = 1; 2) followed by a thermal annealing treatment under S containing atmosphere.
The properties of the CTS absorber are strongly influenced by the morphological and structural characteristics of the metallic stacks precursors that depend on the ED operating conditions. In this case, the influence of electrolyte formulation and applied potential on the microstructure and morphology of the Cu–Sn precursors will be deeply studied. Then, we will investigate in detail how the stacking order of the precursor films affect the microstructure and optical properties of the resultant CTS absorbers. Moreover, our preliminary results of the growth of CTS thin films obtained by an alternative ED approach that we still develop in our laboratory, will be report and compare with the results obtained from a more conventional ED synthesis discussed above.
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[3] M. Adelifard, M. Mehdi, B. Mohagheghi, H. Eshghi, Phys. Scr. 85, 035603 (2012)
[4] P.A. Fernandes, P.M.P. Salom, A.F. da Cunha, J. Phys. D Appl. Phys. 43, 215403 (2010)
[5] D.M. Berg, R. Djemour, L. Gutay, S. Siebentritt, P.J. Dale, X. Fontane, V. Izquierdo-Roca, A. Pérez-Rodriguez, Appl. Phys. Lett. 100, 192103 (2012)