Tuning the morphological and dispersion parameters of electrospun PAN/CZTS nanofibers as a potential candidate for advanced optoelectronic applications

For the first time, Cu₂ZnSnS₄ (CZTS) nanoparticles synthesized through the solvothermal method, were incorporated into polyacrylonitrile (PAN) to improve the morphological and optical properties of PAN/CZTS nanofibers. Fourier transform infrared (FTIR) verified a strong interaction between PAN and CZTS. X-ray diffraction (XRD) analysis showed the semicrystalline PAN matrix and the tetragonal crystal structure for the CZTS. Field emission scanning electron microscopy (FESEM) images presented the formation of quasi-spherical and nanoworm-like geometries for the CZTS and uniform nanofibers with average diameters of 155, 132, 126, and 124 nm in the pristine and nanocomposite films. Transmission electron microscopy (TEM) analysis revealed that CZTS promoted the formation of nanofiber composites with a core-shell structure. The highest absorbance value appeared within the wavelength range of 250–260 nm. The indirect energy gap \({(E}_{{g\; indir}}^{{opt}})\) decreased from 3.7 to 2.81 eV, and Urbach energy increased from 0.28 to 0.79 eV with the addition 2–6 wt.% CZTS. Additionally, the skin depth, extinction coefficient, refractive index, and optical conductivity were studied. The refractive index behavior was studied by employing the Wemple-Di Domenico single oscillator model. The optical susceptibility χ⁽¹⁾, χ⁽³⁾ and nonlinear refractive index n₂ of PAN and PAN/CZTS were enhanced from 0.046 to 0.127 esu, 0.78 to 44.2 esu, and 23.7 to 1034 esu, respectively. The results show that the PAN/CZTS nanofibers are potential optoelectronic devices.

Graphical Abstract