Fabrication And Thermoelectric Characteristics Of The Sb-doped ZnO Microwires

ZnO has attracted widely attention due to its direct wide band gap of 3.37 e V and relatively large exciton binding energy of 60 me V at room temperature,which regarded as one of the most promising candidates for the UV photo-electronic devices.ZnO are pro mising for thermoelectric material because their excellent charge carrier transport properties,thermo-stability and chemical stability.However,there are few studies about thermoelectric microgenerators based on ZnO nano/microstructures,especially on large-size single ZnO microwire(MW).Compare with the nanowire thermoelectric devices,the microwire has a large-size to obtain a stable thermal gradient,so ultralong single microwires with high crystal quality produce better thermoelectric properties.In this paper,we report the synthesis and characterization of different Sb doping contents large-size ZnO MWs by chemical vapor deposition(C VD)method.O n this basis,the thermoelectric generators based on single Sb doped ZnO microwires were fabricated.The Sb doping contents,length,diameter and ultraviolet light influenced on the output characteristics of devices were investigated.The major research achievements are listed below:(1)Large-scale ZnO microwire arrays with different Sb doping contents were grown by chemical vapor deposition method without using metal catalyst.The experimental results showed that the length and orientation of ZnO microwires were improved gradually with increasing Sb contents.The length of the microwires was about 1–2.5 cm.Furthermore,the intensity ratio of the UV and visible emission was increased with increasing Sb contents in the photoluminescence spectrum.These good changes of samples may be related to Sb doping the growth process of ZnO can be act as a surfactant.(2)Thermoelectric generators were fabricated based on single Sb doped large-scale ZnO microwires.The Sb doping contents,length,diameter and ultraviolet light influenced on the output characteristics of devices were investigated.For the devices based on different Sb doping contents ZnO microwires,under a temperature difference of 20 K between two electrodes,the devices can produce a maximum output voltage of about 68 m V,a maximum output current of 782 n A,and maximum output power of about 37.54 n W.Furthermore,when the Sb concentrations were about 1.1%,2% and 3.1%,respectively,the single Sb-doped ZnO microwires showed a Seebeck coefficient of about –3.40 m V/K,–2.80 m V/K and –2.40 m V/K,respectively.In addition,it was found that the output voltages of the thermoelectric device increased with the microwire length,and decreased with the microwire diameters.Moreover,when a UV light,the output current of the device sharp increased,and the reason was researched.The experimental results can be for ZnO micro/nanostructure provides a research foundation in the application of thermoelectric generator.