Controlled Fabrication And Photoelectric Properties Of Tellurium Nanomaterials

Recently,narrow band gap semiconductor nanomaterials have been widely studied because of their unique physical and chemical properties.Among them,as a narrow direct bandgap semiconductor with a bandgap of?0.35 eV,tellurium(Te)displays interesting optical properties and widely used in infrared photoelectric detection,nonlinear optical,thermoelectric,biological sensing and other fields.Currently,considerable efforts have been made to synthesize the Te nanotubes,nanorods,nanowires and nanobelts by various methods.Certainly,solution-based approaches are low-cost and large-scale methods for manufacturing nanomaterials.A variety of solution-based methods for preparation of Te nanowires have been studied in past ten years.Interestingly,although the solution-based methods have been demonstrated to be promising for achieving one-dimensional Te nanostructures,they have drawbacks such as the hazardous chemicals(such as NaBH4,NH2OH,N2H4�H2O and(NH4)2S2)as reducing agents and extreme operating conditions(such as high temperature and microwave assist).Low-temperature green chemical synthesis in aqueous solution is highly desirable because it is an environmentally benign and user-friendly approach,which may be considered to be a relatively practical alternative for industrialization.Herein,we focused on the facile route for the synthesis of the uniform tellurium nanomaterials.We also characterized the photoelectric properties of these nanomaterials.The main research contents are as follows:(1)Uniform tellurium nanowires(NWs),nanorods(NRs),ultra-thin nanowires,nanotubes(NTs)and trifold nanorods(NRs)were synthesized using a facile,environmentally benign solvothermal method with ethylene glycol as solvent,poly(vinyl pyrrolidone)as surfactant and nonhazardous ascorbic acid as reducing agent.The effects of reaction conditions,such as reducing agent,surfactant,solvent,reaction temperature and reaction time on the morphology of the products are investigated meticulously.The growth process and mechanism of these Te nanomaterials are also discussed.(2)The photoelectric properties of the photodetectors based on randomly oriented Te nanowires film,ultra-thin Te nanowires film,trifold Te nanorods film and well-aligned Te nanowires film were studied.At a bias voltage of 1.0 V under infrared radiation with 60.7 ?W.the photocurrent can reach 26.6 mA.The responsivity can reach 86.52 A/W at a bias voltage of 1.0 V under infrared radiation with 16.7 ?W.The rise time is less than 0.1 s,while the decay time is 1.2 s.The rise and decay time of the photodetector based on randomly oriented Te NWs are 109 s and 105 s,respectively.In contrast with structures based on randomly oriented materials,we found that the well aligned Te NWs photodetector greatly enhanced the photocurrent,photoresponsivity and rate.Among them,photoresponsivity of the well aligned Te NWs film was 103 times larger than the randomly oriented.And the response time(rise and decay)of the former was 1.15�103 times shorter than the latter.Furthermore,he reasons for the performance differences between randomly oriented and well aligned Te nanowires film are discussed.