Preparation And Photoelectric Properties Of Sb₂E₃?E=S,Se? Semiconductor Nanomaterials

?₂-?₃??=Sb,Bi;?=S,Se,Te?semiconductor materials have received more and more attention and research due to their low toxicity,environmental protection and superior thermoelectricity and photoelectric properties.As a typical representative,Sb₂S₃ is a direct bandgap?Eg=1.78 eV?semiconductor with a layered structure,which is usually amorphous under low temperature synthesis and grown in orthorhombic crystals at high temperatures.Due to its suitable band gap width,large absorption coefficient,high electron mobility,good photoconductivity,and photovoltaic properties,Sb₂S₃ based materials are widely studied in many optoelectronic devices.At present,there are still many problems to be solved in such material preparation,size/shape control,material surface modification and photoelectric performance enhancement.This paper takes Sb₂S₃ as the main research object and carries out the following research work:1.The synthesis of amorphous Sb₂S₃?a-Sb₂S₃?colloid and interfacial N?Sb nonbonded interaction enhances the photoelectronic performance of PVP-Capped Sb₂S₃ Amorphous Colloids were studied.Using sulfur powder,antimony trichloride as raw material and polyvinylpyrrolidone?PVP?as surfactant,amorphous a-Sb₂S₃colloidal particles with an average size of were prepared by reflux method at 180?;At the same time,while maintaining other synthesis conditions,the addition of 1-Dodecanethiol?DDT?produced the amorphous/crystalline mixed a+c Sb₂S₃.The amorphous and crystalline states were identified by XRD.The TEM results confirmed the yield of the amorphous colloidal particles as well as the mixed amorphous colloidal particles/crystalline micro-nanorods.In the photoelectric performance test,it was found that the photoelectric performance of PVP-coated amorphous a-Sb₂S₃ colloid was better than that of uncoated amorphous colloids;The two-phase mixture exhibits a more pronounced photoconductivity gain than the single-phase a-Sb₂S₃ colloids,and has better photoelectric response and optical switch stability with an order of magnitude of10^-6 A and an on/off ratio?light/dark current ratio?close to 40.In addition,we proposed that the interface non-bond N?Sb interaction between the N atom in the surface coating molecule of PVP and the Sb atom on the surface of a-Sb₂S₃ is considered to be a key factor for enhancing photoconductivity and inhibiting the crystallization of a-Sb₂S₃ colloids.2.The effects of temperature change and DDT modification on the morphology and photoelectric properties of Sb₂S₃ nanorods were investigated.The study found that temperature strongly affects the crystalline state and morphology of Sb₂S₃nanomaterials.The amorphous nanoparticles were synthesized at 180?.Sb₂S₃synthesized at 200??such as 210 and 230??was a crystalline one-dimensional rod-like morphology with an average diameter of 500-600 nm and a length of 5-8?m,which size is more than Sb₂S₃ synthesized at 180?.The one-dimensional rod growth of the crystalline state of Sb₂S₃ is attributed to its special crystal structure anisotropy.Based on the photodetector of ITO/Sb₂S₃/ITO structure,the photoelectric properties of Sb₂S₃nanorods were particularly investigated.The photoelectric response properties of Sb₂S₃nanorods synthesized at 210 and 230?show a weakening trend compared with those of amorphous Sb₂S₃ colloids obtained at 180?.However,the addition of DDT for surface modification in the experiment can effectively enhance the photoelectric properties of Sb₂S₃ nanorods.Sb₂S₃ nanorods modified by DDT show better photoelectric response performance under monochromatic light of 650 nm,550 nm,450 nm and white-light irradiation.As a conclusion,our experimental results show that the photoelectric response performance of 210?+DDT Sb₂S₃ is the best,and the order of magnitude of photocurrent reaches 10^-5A,indicating that the as-obtained Sb₂S₃nanorods have potential application in photodetection.3.The controllable synthesis,morphology and photoelectric properties of ternary Sb₂(Se_xS_1-x)₃ nanorods were explored.Since Sb₂S₃ and Sb₂Se₃ share the same crystal structures,ternary Sb₂(Se_xS_1-x)₃ alloy can be obtained by partially replacing S in Sb₂S₃with Se atoms.The experimental method is to dope Se^2-during the synthesis of Sb₂S₃,and various Sb₂(Se_xS_1-x)₃ nanorods were prepared by changing different Se/S feeding ratios.XRD characterizes the phase change of Sb₂(Se_xS_1-x)₃.It is found that as the concentration of selenium increases,the positions of the diffraction peak gradually shift to the low 2?angle end and the corresponding interplanar spacings become smaller.This lower angle shift is due to the fact that the Se atom?1.98??with a larger lattice constant gradually replaces the smaller lattice constant S atom?1.84??,resulting in an increase in the alloy lattice constant.This continuous change in lattice parameters indicated that there was no phase separation of Sb₂S₃ and Sb₂Se₃ in the sample.Combined with EDS characterization,it was confirmed that the obtained sample was a solid solution of Sb₂S₃ and Sb₂Se₃,not a mixture of Sb₂S₃ and Sb₂Se₃.The TEM results show the average size of the nanorods:60-80 nm in diameter and 300 nm-5?m in length.By adjusting the Se/S reactant molar ratio,the band gap of Sb₂(Se_xS_1-x)₃ can be adjusted over the entire composition range of x=0 to 1,realizing the band gap energy of Sb₂(Se_xS_1-x)₃ nanorods adjustable within the range of at 1.14 and 1.55 eV.Such results reveals that the prepared Sb₂(Se_xS_1-x)₃ nanorods have a broad spectral absorption from visible to near-infrared.The photoelectric properties of photodetector devices based on ITO/Sb₂(Se_xS_1-x)₃/ITO structure were explored.It was found that the photo-response performance of ITO/Sb₂(Se_xS_1-x)₃/ITO devices was enhanced with the increase of selenium concentration.Sb₂(Se_xS_1-x)₃?x=0.85,x=0.75?with higher selenium concentration has obvious photoreactivity,and the order of magnitude of photocurrent can reach 10^-6A,which about two orders of magnitude higher than Sb₂(Se_xS_1-x)₃?x=0.25,x=0.15?with low selenium concentration,showing better photoelectric response and optical switch stability.