Impact of europium (III) on optoelectronic properties of CZTS thin films prepared by spin coating method

The Europium (Eu(III))-doped Cu₂ZnSnS₄ (CZTS) thin films were prepared by spin coating method. Structural, morphological and elemental composition were analysed by X-ray Diffraction (XRD), Raman Spectroscopy and Scanning Electron Microscope with Energy-Dispersive X-ray analysis (SEM–EDX). Optoelectronic properties were analysed by UV–VIS-NIR Spectrophotometer and Van der Pauw Ecopia HMS-3000 Hall Measurement System. The XRD patterns verified the kesterite structure and Eu(III) doping was shown to increase crystallite sizes. High absorption was seen in the visible region of the UV–VIS-NIR spectra, and as the doping percentage was increased, the band gaps were dropping from 1.92 to 1.80 eV. The SEM images exhibited enhanced grain growth from several nano-meters to micrometers along with agglomeration of different sizes. The Hall measurements showed that the undoped CZTS and 1% Eu(III) doped CZTS as p-type semiconductors, suitable absorber layer of thin film solar cells, 2% and 3% Eu(III)-doped samples as n-type semiconductors.