Liquid-phase Synthesis And Characterization Of FeSe₂ Nanomaterial

Iron diselenium(FeSe2)is a promising semiconductor for the thin-film solar cells because of its suitable band gap(Eg= 1.0 eV)and high absorption coefficient(?>105 cm-1).It is important to improve its properties for its application by precisely controlling its sizes,dimensionalities,compositions and crystal structures in nanoscale.In this dissertation,valuable explorations have been carried out on the synthetic strategies and shape control.In preparation,three solution-based routes:hydrothermal method,precipitation method and hot-injection method were tried to synthesize orthorhombic FeSe2 nanocrystals(NCs).Various morphologies of the FeSe2 were achieved by adjusting the kinetic modulation and reaction conditions.Additionally,by changing the precursors,surfactants,reaction time and reaction temperature in the systems,phase-pure,high-quality,shape-controlled and orthorhombic FeSe2 NCs were successfully synthesized.Meanwhile,the probable growth mechanism and fabrication process of the nanocrystals were proposed.Finally,the simple device of FeSe2 NCs were fabricated,and a strong photoconductivity was observed when orthorhombic FeSe2 as the candidate of solar cell for the first time.This will open up a host of applications of FeSe2 in photovoltaic devices with potential for flexible,low-cost power generation.