Electrodepositing Preparation And Photoelectrical Properties Of Pyrite Thin Film

FeS₂ which is pyrite has an appropriate forbidden band gap ?Eg=0.95eV? and high absorption coefficient ?105cm-1?,it is a extremely potential solar battery material for absorption material. It has received extensive attention of the photovoltaic industry since it consists of nontoxic and abundant elements. At present, FeS₂ thin film general prepared by expensive methods such as vapor deposition. But the result films prepared by electrodeposition which is much cheaper always deviation from ideal stoichimetry. In this paper, the precursive Fe-S films were prepared by electrodepositing.The pyrite crystal FeS₂ thin film were expected to obtain by annealing the precursive Fe-S films in sulfurizing atmosphere.First, a electrodeposition of precursive Fe-S films process was investigated. A constant potential process was used to explore the effect of component concentration, solution pH, potential and deposition time. The electrodeposition solution was composed with FeSO₄ or ?NH4?₂ Fe?SO₄?₂ as the source of Fe element, and Na₂S₂O₃ as the souce of S element. When FeSO₄ as the source of Fe element, the amorphous precursive Fe-S films with S:Fe= 1.25:1 can be achieved using the condition of 0.01M FeSO₄ with 0.02M Na₂S₂O₃; pH=4.0; deposition potential of -1.00V?vs. SCE?; deposition time of 900s. When ?NH4?₂ Fe?SO₄?₂ as the source of Fe element, the amorphous precursive Fe-S films with S:Fe=1.29:1 can be achieved using the condition of 0.01M ?NH4?₂ Fe?SO₄?₂ with 0.02M Na₂S₂O₃; pH=3.8; deposition potential of-0.90V?vs. Ag/AgCl?; deposition time of 800s.After annealing the precursive Fe-S films which prepared by two kinds of Fe source in sulfurizing atmosphere,we found that the crystallization quality and ratio of elements were related to the annealing temperature and annealing time.The XRD and Raman pattern showed the pure pyrite phase film after sulfuring at 500? which took 1h. Then we characteristiced the annealed film which made from FeSO₄.UV-VIS-NIR tests showed that the band gap of film was about 0.95eV.Hall effect tests showed that carrier concentrain was 3.922×10¹⁷cm^-3; carrier mobility was 8.236cm²·V^-1·s;resistivity was 0.1060 Ohm-cm. Its performance was good, was able to be the absorb layer of solar cells. And we also characteristiced the annealed film which made from ?NH4?₂Fe?SO₄?₂.UV-VIS-NIR tests showed that the band gap of film was about 0.97eV.Hall effect tests showed that carrier concentrain was 2.082×10¹⁷cm^-3; carrier mobility was 7.716cm²·V^-1·s;resistivity was 0.3885 Ohm·cm. Its performance was also good, was able to be the absorb layer of solar cells,too.