Solution-based deposition of wurtzite copper zinc tin sulfide nanocrystals as a novel absorber in thin film solar cells

摘要

Cu_2ZnSnS_4 (CZTS) is considered to be one of the most promising absorber materials capable of driving the development of low cost and high performance photovoltaic. Its direct and tunable band gap of 1.4-1.6 eV, high absorption coefficient over 10~4 cm~(-1), earth abundant and non-toxic constituents give it a number of advantages and rise it above other thin film absorber materials like polycrystalline cadmium telluride, copper indium diselenide and its combinations with gallium and/or sulfur (Cu(In,Ga)(S,Se)_2). In this present study, wurtzite CZTS nanocrystals have been prepared by a sol-gel route associated to spin coating. The CZTS samples have been characterized structurally by X-ray diffraction (XRD) and Raman spectroscopy, morphologically by scanning electron microscope (SEM) and optically by a vis spectrophotometer. XRD result and Raman analysis revealed a wurtzite structure. SEM studies showed a condensed surface composed of agglomerated nanocrystals and optical absorption showed a band gap of 1.55 eV suitable for photovoltaic applications.