Nonlinear optical properties of Cu2ZnSnS4 nanocrystal thin films and its constituents thin films

In this study, Cu2ZnSnS4 nanocrystal and its constituents’ copper, zinc and tin were grown separately by pulsed laser deposition technique as thin films, and their linear and nonlinear optical properties have been investigated. Linear optical properties were analysed with UV–Vis absorption spectra. Elemental composition of Cu2ZnSnS4 thin films was analysed by scanning electron microscope–energy dispersive X-ray. The nonlinear optical properties for Cu2ZnSnS4 nanocrystal and its constituents’ copper, zinc and tin have been determined applying z-scan method with closed and open aperture measurements using femtosecond laser (90 fs) pulses which deliver fundamental wavelength at 800 nm. Furthermore, Cu2ZnSnS4 nanocrystal ultrathin films and copper, zinc and tin thin films nonlinear refractive indexes n2 were calculated about ~ 10−13 cm2/W, their nonlinear absorption coefficient β are calculated about ~ 10−12 cm/W. Third-order susceptibilities for nano-crystal ultra-thin films and copper, zinc, and tin thin films were determined to be 10−11 esu.