Preparation And Photoelectric Properties Of Copper-Based Oxide/ZnO Composites

Among the optoelectronic devices,the research of ultraviolet detection devices has become a hot topic widely concerned at home and abroad.Ultraviolet optoelectronic detection technology can be applied not only to the defense and military fields,but also to people's daily life,including the detection of the environment,flame irradiation,and biological analysis.The one-dimensional ZnO semiconductor nanomaterial has a band gap of 3.37 eV and an exciton binding energy of 60 meV.Compared with GaN,the excitons of one-dimensional ZnO semiconductor nanomaterials can exist stably at room temperature because of the larger exciton binding energy,which hold the great potential candidates for the short-wavelength lasers,LEDs and ultraviolet photodetectors.In this paper,in order to improve the optoelectronic properties of ZnO semiconductor nanomaterials,the use of intrinsically p-type semiconductor nanomaterials?Si and CuO?and n-type ZnO semiconductor nanomaterials are combined to introduce heterojunctions.The energy band bending at the interface of different materials promotes the separation of photogenerated carriers,which affects transmission of photogenerated carriers improves the photoelectric performance of Zn O semiconductor nanomaterials.The main research contents of this paper are as follows:?1?The sol-gel-assisted hydrothermal method was used to prepare the ZnO nanorod arrays and test their photoelectric properties.Orthogonal experimental design was adopted,and the photoelectric sensitivity was used as an index to obtain its relative optimal process parameters:the sol-gel Zn²⁺concentration is 0.3 mol/L,the hydrothermal[Zn²⁺]/[?CH₂?₆N₄]concentration ratio is 1:3,the hydrothermal Zn²⁺concentration is 0.05 mol/L,and the hydrothermal reaction temperature is 90°C.The characterization and analysis of the samples were prepared by the most technological processes.The dark current,photocurrent and photoelectric sensitivity of the ZnO nanorod arrays photoelectric device are 4.89?A,996.33?A,and 203.7,respectively.Then the hydrothermal[Zn²⁺]/[?CH₂?₆N₄]concentration ratio was used as a single factor to prepare ZnO nanorod arrays and study their photoelectric properties.When the hydrothermal[Zn²⁺]/[?CH₂?₆N₄]concentration ratio is 1:2.5,the photoelectric performance of the prepared ZnO nanorod arrays is relatively good,with a dark current of 3.98?A,photocurrent of1045.77?A.and photoelectric sensitivity of 262.8.In addition,the photoelectric response rise and fall time of that are 53.6 s and 139.8 s.?2?The sol-gel-assisted hydrothermal and water-bath methods were used to grow ZnO nanorod arrays and CuO@ZnO nanorod arrays composites on FTO substrates and study their photoelectric properties.The results show that the photoelectric sensitivity of the ZnO nanorod arrays and CuO@ZnO nanorod arrays composites materials are 153.6 and 380.37,respectively.The photoelectric rise time and fall time of CuO@ZnO nanorod arrays composites are much smaller than those of Zn O nanorod arrays.This is because ZnO and CuO form a good pn junction,which accelerates the separation and recombination of photo-generated electrons and holes.After that,CuO@ZnO nanorod arrays composites were prepared by single factor and its effects on structure,morphology and optics were studied,and the better preparation of CuO@ZnO nanorod arrays composites was optimized.The relative optimal process parameters were obtained:the Cu²⁺concentration is 0.04 mol/L,the time is45 s,the Cu²⁺source is CuSO₄·5H₂O,the solution temperature is room temperature,and the annealing temperature is 500?.The dark current,photocurrent and photoelectric sensitivity of the CuO@ZnO nanorod arrays composites photoelectric device are 0.057?A,138.65?A and 2432.4,respectively.In addition,the photoelectric response rise time of that is 46 s,and the fall time of that is 40 s.?3?The optimized CuO@ZnO nanorod array composites materials were doped with different concentrations using Sn,La and Sb,and their effects on the structure,morphology,optical and ultraviolet photoelectric properties of the samples were studied.The results show that when the[Sn⁴⁺]/[Cu²⁺]concentration ratio is 2%,the darkcurrent,photocurrent and photoelectric sensitivity of the prepared Sn-doped CuO@Zn O nanorod arrays composites photoelectric device are 0.038?A,141.52?A and 3724.2,respectively.Compared with the undoped CuO@ZnO nanorod array composite materials photoelectric device,its photoelectric performance is better.However,when the[Sn⁴⁺]/[Cu²⁺]concentration ratio was increased to4%and continued to increase,the larger concentration of Sn doping prevents the adsorption of the hydrated copper ion[Cu?H₂O?₄]²⁺substance?complex?in on the surface of ZnO nanorods,the content of CuO nanosheet films on the surface of ZnO nanorods is reduced,so that the heterojunction formed is reduced.Therefore,the photocurrent and photoelectric sensitivity of Sn-doped CuO@ZnO nanorod arrays composites photoelectric device are reduced.La doping changed the morphology of CuO nanomaterials on the surface of ZnO nanorods,and introduced CuSO₄.As the[La³⁺]/[Cu²⁺]concentration ratio increases,the dark current of La-doped CuO@ZnO nanorod array composite photoelectric device is effectively reduced,the photoelectric sensitivity of that is effectively increased,but the photocurrent of that is reduced.When the[La³⁺]/[Cu²⁺]concentration ratio is 4%,the darkcurrent,photocurrent and photoelectric sensitivity of the prepared La-doped CuO@Zn O nanorod arrays composites photoelectric device are 0.026?A,106.63?A and 4101.1,respectively.Sb doping prevents the hydrated copper ion[Cu?H₂O?₄]²⁺species?complex?from adsorbing on the surface of ZnO nanorods.As the[Sb³⁺]/[Cu²⁺]concentration ratio increases,CuO on the surface of ZnO nanorods are reduced sharply to non-existence.Therefore,after high temperature annealing,Sb³⁺ions are adsorbed on the surface of ZnO nanorods to replace Zn²⁺in the lattice with a substitution form to prepare Sb-doped ZnO nanorod arrays.When the[Sb³⁺]/[Cu²⁺]concentration ratio is 8%,the dark current,photocurrent and photoelectric sensitivity of the prepared Sb-doped Zn O nanorod arrays photoelectric device are 2.638?A,1372.73?A and 520.3,respectively.Compared with the undoped ZnO nanorod array UV photodetector,its photoelectric performance of that is better.The results of three doped samples were compared and analyzed.When the[La³⁺]/[Cu²⁺]concentration ratio was 4%,the photoelectric performance of the prepared La-doped CuO@ZnO nanorod array composite photoelectric device is relatively good.And Sb doping on a single ZnO nanorod arrays can also increase its photoelectric performance.?4?Ag and Au were used to modify the optimized ZnO nanorod array and CuO@ZnO nanorod array composites,and their effects on sample structure,morphology,optical and ultraviolet photoelectric properties were studied.The results show that the surface modification of Ag can effectively improve the photoelectric performance of ZnO nanorod array.With the increase of Ag nanoparticle content and size,the dark current of the ZnO nanorod array photoelectric device first decreases and then increases,while the photocurrent and photoelectric sensitivity of that first increase and then decrease.When the ultraviolet light irradiation time was 150 min,the darkcurrent,photocurrent and optoelectronic sensitivity of the prepared Ag surface-modified ZnO nanorod array photoelectric device are 0.332?A,1395.75?A and 4204.1,respectively.Ag surface modification can effectively improve the photoelectric performance of CuO@ZnO nanorod array composite.As the content and size of Ag nanoparticles increase,the dark current of Ag surface-modified CuO@ZnO nanorod array composite optoelectronic devices decreases first and then increases,and the photocurrent and photoelectric sensitivity increase and then decrease.The darkcurrent,photocurrent and optoelectronic sensitivity of the prepared Ag surface-modified CuO@ZnO nanorod array composite UV optoelectronic device are 0.018?A,465.21?A and 25845.0,when the ultraviolet light irradiation time was 120 min,respectively.The surface modification of Au can effectively improve the photoelectic performance of ZnO nanorod array.As the content and size of Au nanoparticles increases,the dark current of the ZnO nanorod array optoelectronic devices decreases first and then increases,while the photocurrent and photoelectric sensitivity increase and then decrease.When the UV light irradiation time is 40min,the darkcurrent,photocurrent and optoelectronic sensitivity of the Au surface-modified ZnO nanorod array optoelectronic devices are 0.151?A,1994.89?A and 13211.1,respectively.The surface modification of Au can effectively improve the photoelectric performance of CuO@ZnO nanorod array composite.As the content and size of Au nanoparticles increase,the dark current of the Au surface-modified CuO@ZnO nanorod array composite optoelectronic device decreases first and then increases,and the photocurrent and sensitivity increase and then decrease.The dark current,photocurrent and optoelectronic sensitivity of the prepared Ag surface-modified CuO@ZnO nanorod array composite optoelectronic device are 0.012?A,438.65?A,and 36554.2 when the UV light irradiation time was 40 min,respectively.The optoelectronic properties of Ag and Au-modified ZnO nanorod arrays are compared.When the UV light irradiation time is 40 min,the dark current of the Au surface-modified ZnO nanorod array optoelectronic device is relatively smallest,and the photocurrent is relatively maximum,its photoelectric sensitivity is relatively maximum.Comparing with the optoelectronic properties of Ag and Au-modified CuO@ZnO nanorod array composites,when the UV irradiation time is 40 min,the dark current of the prepared Au surface-modified CuO@ZnO nanorod array composites is relatively minimum,the photocurrent of that is relatively maximum,and its photoelectric sensitivity of that is relatively maximum.