Numerical study of the effect of diode laser-induced optical, thermal, and residual stresses on CZTS thin-films

This paper presents a numerical study of the continuous wave (CW) diode laser processing of Cu2ZnSnS4 (CZTS) thin-film. The CZTS film’s structural, optical, surface morphological, and electrical properties improvement due to the localized and instantaneous heating provided by the diode laser mandates a detailed understanding of how laser processing affects the CZTS thin-film during thermal treatment to ensure a high-quality processing result as well as optimization and characterization. However, understanding of such process suffers from the restricted accessibility as most of the important phenomena occur inside the film during a very short duration time, where numerical simulations can serve as a valuable alternative to gain accessibility. This contribution, therefore, presents a numerical approach to examine the CW diode laser-induced thermal effect on the CZTS thin-film. A numerical model in OpenFOAM has been developed to elucidate the influence of laser processing parameters on the optical, heat transfer, and residual stress, as well as design architecture, of the CZTS thin-films. The model results predicted that the inappropriate settings of the laser parameters, as well as the thickness of the CZTS films, generate thermal gradient within the film and hence induce delamination and propagation of crack at the interfaces. The developed model helped in understanding the laser-induced thermal behavior of the CTZS thin-film and can be utilized as a guide to using lasers as an effective tool for fabricating the high-efficiency CZTS thin-film based solar cells.