Cu2ZnSnS4 Films Properties Deposited by Spray Pyrolysis, Subjected to a Combined Novel Thermal Treatment: CSS Sulfurization and RTA Post-Treatment

CZTS films were obtained by spray pyrolysis, a low-cost technique implemented on an industrial scale. Sulfurization processes generally enhance CZTS properties for its use in solar cells; however, these require high temperatures and long times. In this work, CZTS films properties were studied after being subjected to a combined novel thermal treatment which involved two stages. Sulfur incorporation using close space sublimation technique (CSS) at a temperature (TCSS) in the 350-500 degrees C range for 60 s, and after a rapid thermal annealing post-treatment (RTA) at TRTA = 500 degrees C for 10 s, with a heating ramp of 5 degrees C/s under argon atmosphere. Morphological, structural, chemical composition, optical and electrical properties were studied for CZTS films subjected to CSS as CSS+RTA treatments for all TCSS values. From the results, efficient sulfur incorporation by CSS was obtained without substantial sulfur concentration loss after RTA treatment, as-sociated with the short treatment time. In addition, significant enhancement of crystalline quality and electrical resistivity diminished of the films is obtained after the CSS+RTA process for all TCSS. CZTS films with the best properties are those obtained at TCSS of 400 degrees C, having Cu/(Zn+Sn) = 0.79 and Zn/Sn = 1.3 ratios, a direct bandgap value of 1.5 eV, and resistivity of 4 ohm-cm. These films can be candidates for their characteristics as an absorbent layer in solar cells.(c) 2023 Elsevier B.V. All rights reserved.