Synthesis of chemical spray pyrolyzed Cu2FeSnS4 thin films for solar cells

In this paper, we have successfully prepared Cu2FeSnS4 (CFTS) thin films by a facile spray pyrolysis method. In order to optimize the synthesis conditions of the CFTS thin films, two series of experiments were performed. In the first series, the thin films were deposited at a substrate temperature of 370 degrees C for different spray durations (t(d)) of 20, 40 and 60 min. And in the second, the CFTS thin films were annealed in the sulfur atmosphere at a temperature of 450 degrees C for 30 min. Moreover, the X-ray diffractograms showed that the as-deposited and the post-annealed CFTS thin films revealed a stannite structure. The post-annealed CFTS thin films are considered as an ideal absorber in solar cells because of a large absorption coefficient (10(5) cm(-1)) and a direct band gap (1.55 eV). The activation energies E-a obtained from both angular frequency and DC conductivity are found to be 1 and 0.97 eV, respectively.