In this work,a simple and facile one-pot oleylamine solvothermal synthetic method was developed to synthesize Cu_2ZnSnS_4(CZTS) nanocrystals.And the Cu_2ZnSn(S,Se)_4(CZTSSe) thin films were prepared by selenizing CZTS nanocrystals.The obtained CZTS nanocrystals and CZTSSe films were studied using X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDX),and ultraviolet–visible spectrophotometer(UV–Vis).TEM results show that the sphere–like CZTS nanoparticles with diameter between 12 and 35 nm are polydispersed.XRD studies indicate that the prepared CZTS nanocrystals form kesterite crystal structure,and the CZTSSe films with kesterite crystal structure are also obtained at the annealing temperatures of 500 and550 °C.In particular after annealing at 500 °C for 20 min,the CZTSSe film exhibits a smooth,uniform,crack-free,and large-grained topography and possesses Cu-poor and Sn-rich composition.Moreover,it shows strong optical absorption from visible to near-infrared(IR) region,and its optical band gap(Eg) is found to be about 1.44 e V.
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