Synthesis And Optoelectronic Properties Of Cu₂S And CuInS₂Nanostructures

This thesis introduces two different kinds of metal sulfide nano materials，Cu₂S andCuInS₂. Cu₂S is a p-type of indirect band gap of semiconductor, and the band gap of bulkmaterial is close to1.2eV, which would have potential application value inoptoelectronic filed. As abundance of Cu₂S has been found existing in the form ofchalcocite in nature, Cu₂S is a kind of low cost and outstanding optoelectronic material.So far, Cu₂S has been used in preparing solar cell, Li-ion battery, photoelectric device,photocatalytic material and some other photoelectric applications. Today people begin toapply it to fabricate flexible liquid photoelectric device and focus on how to improve thestability of Cu₂S material under the stimulation of illumination. So the research on theCu₂S would have some potential application value in the future. CuInS₂is a kind ofsulfide of Ⅰ-Ⅲ-Ⅵ ternary compound. It is a P-type semiconductor of the band gap of1.5eV which has a great absorption coefficient towards solar energy light, and it is also adirect band gap compound with chalcopyrite structure. In addition, it can maintainstability under the long time illumination stimulation. So in recent years, it has beenlargely used in the preparation of light absorbing materials in solar cell field and somesignificant results have been obtained through these investigates. So it is significant toresearch the optoelectronic property of CuInS₂and it might provide some reference andassistance to enhance its photoelectric performance in the future.This thesis firstly introduces Cu₂S nanostructure which is directly synthetized on Cufilm with the simple liquid phase method. Then we use PDMS as a flexible substrate totransfer Cu₂S from Cu substrate and fabricate flexible Cu₂S light detector successfully.Finally, we apply it to detect near infrared and UV light and some good results haveobtained through our testing. And we also use the material to make the gas sensors tomeasurement its responsibility to some kinds of gas. The results show that Cu₂S hascertain response to NH3. Finally, we also apply it to make quantum dot sensitization solarcells（TiO₂as the photo anode, CdS quantum dot as the sensitization）, and through the experimental results we find that the solar cell has a higher optoelectronic conversionefficiency when using Cu₂S as the photocathode instead of Pt electrode.We also synthesis two different kinds of CuInS₂nanostructures and investigate theiroptoelectronic properties. Firstly, two different liquid phase methods, hydrothermalmethod and reflux method, have been used to synthesis materials. And spheroidal andflowerlike structures are obtained respectively. Then we assemble the FTO glass with Ptcounter electrode into the photoelectric device. At last, we test its photoelectric propertywith illumination stimulation and find that sample of flowerlike nanostructure shows abetter photoelectric performance than that of spheroidal structure. For the sake ofimproving photoelectric performance, we attempt to add grapheme into the sample. It isfound that the addition of graphene has improved the performance of material and wetestify that the increase of photocurrent density is not offered by the graphene whichmight be only promoting electronic transmission.