Exploration of structural and optoelectronic behaviour of mechanochemically synthesized earth-abundant phase pure Cu2FeSnSe4

A solvent-free mechanochemical method has been employed to synthesize the eco-friendly photo absorber Cu2FeSnSe4 (CFTSe) semiconductor using earth-abundant materials. A single-phase quaternary chalcogenide CFTSe was achieved during continuous milling, confirmed by powder X-ray diffraction along with Rietveld refinement and Raman analysis. The material, crystallized in a tetragonal structure (a = b = 5.68, c = 11.35 & Aring;), was verified through sharp diffraction peaks and high-resolution transmission electron microscopy, which indicated (112) orientation with d = 3.2 & Aring;. FESEM and EDS showed particles close to uniform size and stoichiometric composition. Optical properties were analyzed via UV-Vis spectroscopy, revealing an absorption coefficient of similar to 10(4) cm(-1) and a band gap of 1.1 eV. XPS analysis identified various valence states, while Hall measurements confirmed the p-type nature with a carrier concentration of 3.29 x 10(19) cm(-3) and a mobility of 16.8 cm(2) V-1 s(-1). The material demonstrated thermal stability up to 520 degrees C, making it suitable for photovoltaic and semiconductor applications.