Synthesis Of One Dimensional Wurtzite Semiconductor Materials And The Study Of Their Photoelectrical Properties

Ternary and quaternary Ⅰ-Ⅲ-Ⅵ2semiconductor compound, such as CuInS2and CuInxGa1-xS2, is an important class of materials in solar cells and has attracted successive attention in recent years because of the growing demand for clean and unlimited source of energy. The synthesis of high quality nanocrystals with controlled stoichiometry and phase is vital in the fabrication of thin film solar cells. The shape, structure, and composition of the nanocrystals play an important role in determining the optical properties of the materials and the ultimate cell performance. Further, such one-dimensional ternary nanomaterials would provide continuous pathways for charge carrier transport and well-defined nanoscale domain with clearly identifiable grain boundaries. We synthesized wurtzite ternary and quaternary semiconductor nanoribbons (CuInS2, CuInxGa1-xS2) by using CU1.75S as catalyst and demonstrated that wurtzite CuInS2nanowires could be synthesized via Ag2S-catalyzed growth in solution. The investigation of the optoelectronic property indicates that as-synthesized materials are enhanced photo responsive. The main contents are as follows:(1)The single crystalline wurtzite ternary and quaternary semiconductor nanoribbons (CuInS2, CuInxGa1-xS2) were synthesized in solution. Detailed investigation of the growth mechanism indicates that Cu1.75S nanocrystals is formed firstly and act as catalyst for the further growth of the nanoribbons. We focus on the growth of single crystalline wurtzite CuGaS2nanoribbons, the Cu1.75S nanocrystals formed firstly and played the catalytic roles for the formation and growth. But they were consumed gradually and when they exhausted, the growth of the nanoribbon stopped. Photoresponses of the CuGaS2nanoribbons were evaluated by I-V curves based on CuGaS2film fabricated by drop-casting method. The photocurrents of CuGaS2film showed almost17-fold increase under illumination than in the dark, indicating that the as-synthesized CuGaS2nanoribbons are excellent photoactive materials for solar cell.(2)We have demonstrated that wurtzite CuInS2nanowires could be synthesized in solution via Ag2S-catalyzed growth. Photoresponses of CuInS2nanowires were evaluated byⅠ-Ⅴ curves of CuInS2film. The enhancement of photoresponsive current of CuInS2film is believed to be attributed to the single crystalline nature and one-dimensional structure of nanowires.The successful preparation of those nanoribbons provides us an opportunity to study their photovoltaic property. Furthermore, this facile method could open a new way to synthesize other various nano-structured semiconductors such as CuInSe2and CuInxGa1-xSe2for applications in solar cell and other fields.