Designed Synthesis Of Bi, Sb-Chaocogenide Semiconducting Nanostructures And Their Applications In Photodetectors

Bi, Sb-chaocogenide nanostructures are typical narrow band semiconductors and have attracted wide attention due to their significant size-or dimensional-dependent properties. Among these materials, antimony sulfide(Sb2S3), bismuth sulfide(Bi2S3), antimony selenide(Sb2Se3) and) are promising candidates for next generation of electron and photoelectron device due to their excellent electrical and optical properties. We have for the first time fabricated ultrathin Bi2S3nanosheets with thickness down to2.2nm and ultrathin Sb2Se3nanowires with diameters below20nm. Both the ultrathin Bi2S3nanosheets and ultrathin Sb2Se3nanosheets based flexile photodetectors exhibit high performance. We have developed the hydrothermal methods for the synthesis of and the Sb2Se3nanowires. Meanwhile, we have investigated the photoresponse of1D single-crystalline SbSI microrods and the photothermal response of the Sb2Se3nanowires for the first time. The main parts of the results are summarized as follows:1.In this paper, an alternative facile ethanol solvothermal process is firstly introduced to synthesize ultrathin Bi2S3nanosheets with thickness down to2.2nm. To explore the optoelecctronic properties of the new2D-like materials, a flexible photodetector has been fabricated based on the nanosheet-nanosheet film via a facile deposition process on flexible plastics (polyethylene terephthalate, PET) substrates. The resultant ultrathin Bi2S3-based photoconductor shows high sensitivtity to visible-near infrared light from405to780nm with a high external photoresponsivity up to4.4AW"1, high detectivity of～1011Jones, and relatively fast response time as～10μs, which demonstrates much better performance than commercial Si photodetectors and many other2D nanostructured photodetectors. In addition, the device displays high flexibility and durability under detailed measurement. The high repsonsitivity and fast response time can be attributed to the contact quality and nanosheet-nanosheet junction film.2. An alternative facile organometallic synthetic route is developed for the growth of ultrathin Sb2Se3nanowires with diameters ranging from10to20nm and length up to30μm via the reaction of triphenylantimony with dibenzyldiselenide in ethanol at200℃for16h using oleylamine and PVP as surfactants. Especially, flexible photodetectors employing ultrathin Sb2Se3nanowires film have been firstly fabricated on PET and ordinary printing paper substrates, which demonstrate high performance. The excellent flexibility and durability of the photodetectors based on the Sb2Se3nanowires are desirable for practical application in high performance flexile optoelectronic devices with low-cost, portability, and mechanical stability.3. We have developed an alternative, rapid and low temperature hydrothermal method for the synthesis of1D single-crystalline SbSI microrods at160℃for4h. This method is the most highly efficient and low-cost for the large scale synthesis of the SbSI crystals up to date. Meanwhile, the individual SbSI microrod based photodetector equipped with ITO electrodes is fabricated and demonstrated in the work for the first time, and the device exhibits a remarkable response to visible light with an on/off ratio up to727, a detectivity of2.3×108Jones and a noise equivalent power of1.7×10-10W/HZ1/2. It is important that the fast response/recovery times (<0.3s) can further illustrate the high sensitivity of the device.4. Ultra-long orthorhombic Sb2Se3nanowires with high aspect ratio have been fabricated via the facile alternative organometallic synthetic route from the reaction of triphenylantimony and dibenzyldiselenide in oleylamine at220℃without any other additives. The formation and anisotropic growth of the Sb2Se3nanowires is investigated and proven to be mainly due to the intrinsic property of the crystal with orthorhombic structure although oleylamine plays important role in the formation of the Sb2Se3nanowires with uniform diameters. Interestingly, the length of the nanowires can be elongated by increasing reaction time without varying diameters with the assistance of oleylamine. The Sb2Se3nanowires based photodetector exhibits a remarkable response to visible light with a response time of0.14s. Especially, the photothermal response of the Sb2Se3nanowires was firstly investigated under the illumination of light (320-390nm,400-450nm). As compared to bulk Sb2Se3, the Sb2Se3nanowires exhibit two times higher ability for light-to-heat conversion more than that of the bulk.