Low temperature synthesis of iron pyrite (FeS2) nanospheres as a strong solar absorber material

Phase pure iron pyrite (FeS2) nanosphere morphology was synthesized by a solvothermal route an alternative to colloidal synthesis by utilizing an ethylene glycol and benzylamine as a solvent and structure directing ligand at 160 °C for 12 h in Teflon lined autoclave. The as obtained nanospheres were in average ∼50 nm diameter with a smooth surface and well mono-disperse as observed by the FESEM images. The XRD analysis shows a typical iron pyrite crystal phase with 2θ position at 28.23°, 32.76°, 36.84°, 40.48°, 47.32° and 56.01° without any impurity peaks. The Raman spectra further confirmed the phase pure pyrite structure. The UV-Vis and PL spectra shows excellent solar absorbance with a band gaps of 1.35 eV close to the direct band gap (1.38 eV) of pyrite materials, however the photoluminescence spectra shows a band gap of 1.39 eV close to the direct band gap. The obtained nanosphere morphology was highly promising as an excellent solar absorber material for the photovoltaic application.