Controllable Synthesis And Photoelectric Properties Of Low-temperature Growth Of One-dimensional Eu-doped ZnO Nanowire Arrays As Photoanote

ZnO,a wide bandgap semiconductor material with hexagonal wurtzite structure,features high exciton binding energy,stable chemical property,excellent photoelectric and force-electricity characteristics.However,electrical and optical performance of one-dimensional?1D?ZnO nano material is improved by nanometer effect.Thus,it manifests outstanding photoelectric properties including large carrier mobility,small electrical resistivity,high electronic transmission efficiency and strong optical trapping capacity.Therefore,it shows wide application prospect in the field of solar cell as photo-anode material.However,its photoelectric property is influenced because of the limitation of ZnO bandgap width.Doping is a main pathway to enhance photo-anode photoelectric property of solar cell.In this paper,the research objective is to dope Eu into 1D ZnO nanowire?NW?array so that the photo-anode could obtain higher photoelectron transmission rate&efficiency and its optical trapping capacity could be improved designated to enhance photoelectric conversion efficiency of solar cell.Because of great difference in physicochemical properties such as ionic radius and ionization energy between Eu and Zn,it is hard to dope Eu into ZnO crystal lattice evenly under normal temperature condition.To overcome this barrier,Eu-doped 1D ZnO NW array is successfully realized through hydrothermal reaction under united assistance of two surfactants namely polyethyleneimine?PEI?and hexamethy lenetetramine?HMTA?.In addition,it is assembled into dye-sensitized solar cell?DSC?as photo-anode.More,the doping and growth mechanism of ZnO NW is studied using Mannich Reaction Theory.On the other hand,microrod of polyaniline?PANI?is recombined with ZnO NW by electrochemical approach to obtain heterostructure.The main research contents and results are as below:?1?Under the assistance of HMTA,1D ZnO NW array is synthesized on the surface of FTO conductive glass by hydrothermal reaction.The morphology,structure,crystallinity and photoelectric property of the product are characterized by adopting measures such as:scanning electron microscope?SEM?,X-ray diffraction?XRD?,UV-vis spectrum and photoluminescence?PL?spectra.According to the result,it shows that ZnO NW grows on FTO vertically in good order and NW shows hexagonal wurtzite single-crystal structure.During growth reaction process of ZnO NW array,the microstructures of ZnO nanowires are different in different annealing temperatures of ZnO seed layers.The nanocrystalline crystal structure obtained at the annealing temperature of 380?is the most ideal,so the reaction is Annealing temperature of380?is appropriate.The higher the temperature anneal on ZnO seed crystal layer while the smaller the diameter of obtained ZnO NW and the longer its length.Along with the reduction in diameter of NW,the more obvious small size effect will be brought to ZnO NW and blue-shifted phenomenon will occur to UV absorption spectrum.In consequence,it enhances its ability of ZnO to capture photon so as to be favorable for enhancing photoelectric conversion efficiency of solar cell.?2?Eu-doped ZnO NW array photo-anode is prepared and assembled into DSC by hydrothermal reaction under united assistance of PEI-HMTA.The morphology&structure,crystalline structure and photoelectric property of NW array are characterized and photovoltaic performance of DSC is tested by SEM,transmission electron microscope?TEM?,selected area electron diffraction?SAED?,energy dispersive X-ray?EDX?,element map image,XRD and PL spectrum.The result manifests that the synthesized Eu-doped ZnO NW array keeps the original morphology&structure of ZnO NW.Additionally,the crystal structure is not damaged because of doping.XRD displays that diffraction peak of Eu-doped ZnO NW corresponds to ZnO standard substance of JCPDS card No.89-1397 released by powder diffraction JCSEE.It indicates that the synthesized Eu-doped ZnO NW features good hexagonal wurtzite structure.Simultaneously,according to TEM,SAED,EDX and element map image,it's shown that Eu is completely incorporated into crystal lattice of ZnO NW crystal lattice,and some replace the position of Zn in crystal lattice and are evenly distributed.The crystal is of hexagonal wurtzite single-crystal structure.PL spectrum displays the sideband UV emission peak intensity of doped ZnO NW array at 410nm is enlarged along with the increase in doping proportion.Besides,a visible optical defect emission peak with the width of 520nm is available.Its intensity is similarly enlarged along with the increase in doping proportion.This characteristic is applicable to active layer or photoelectric conducting layer of photoelectric devices.Compared with Tb&Gd,the emission intensity of Eu-doped ZnO nanowire arrays in PL spectrum is stronger,which shows that it is the ideal photo-anode material.DSC photovoltaic performance test shows that photovoltaic performance of DSC of Eu-doped ZnO NW array photo-anode greatly improved,of which 6%Eu-doped samples feature optimal photoelectric conversion performance.J_sc and?reach 5.30 mA·cm^-2 and 2.64%respectively,the highest level in all samples.Besides,DSC of Eu-doped ZnO NW array photo-anode features higher photoresponse performance at full-wave band of visible light.?3?In study on growth response mechanism of Eu-doped ZnO NW,the intermedium of response is characterized by measures such as FTIR.Besides,the influences of PEI on morphology,structure and photoelectric property of NW are observed by SEM and PL spectrum.According to the result,it manifests that Eu-doped ZnO NW array growth response experiences six mutually associated reaction processes in PEI-HMTA system:?a?chelation reaction of PEI and Zn²⁺&Eu³⁺;?b?protonation reaction of PEI and NH₃;?c?decomposition reaction of HMTA;?d?Mannich reaction of HCHO and PEI;?e?formation of precursor of Eu-doped ZnO;?f?dehydration synthesis of precursor of Eu-doped ZnO,ZnO NW array forming doped state,of which PEI is the key factor of whole doping growth reaction process.It both plays a role in modifying the growth of ZnO NW and makes it become longer and thinner.In the meantime,it also facilitates doping of Eu and enables ZnO NW to capture more photoelectrons and higher transmission rate,which is critical to improve photovoltaic performance of DSC.In addition,a novel chiral Pt?II?complex was synthesized by hydrothermal method with PEI,and its interaction with G-quadruplex DNA was studied.The results showed that the complex showed a high DNA binding affinity.?4?The compound of PANI microrod/Eu-doped ZnO NW array is synthesized and the heterostructrue is constituted by electrochemical and cyclic voltammetry.Besides,its morphology and structural performance is characterized by measures including SEM,FTIR and UV-vis.The result shows that ZnO NW is not damaged and its morphology and structure is well kept during the formation of heterostructrue of PANI microrod/Eu-doped ZnO NW array.PANI microrod grows on the surface of ZnO NW array.The both contact each well.PANI microrod shows cylindrical structure.The synthesized PANI features semiconductor property.Electrochemical tests show that the maximum specific capacitance of PANI microrod/Eu-doped ZnO NW array is as high as 629 F g^-1at current density of 0.5 A g^-1 and the cycling stability of PANI microrod/Eu-doped ZnO NW array composite material exhibits a high stable and 90.3%of the specific capacitance can still be retained after 200 cycles.Moreover,the coulombic efficiency remains as high as 94.6%after 200 continuous cycles.Therefore,the outstanding electrochemical performances may render this PANI microrod/Eu-doped ZnO NW array a high promising electrode material for high performance supercapacitors in practical application.