The Fabricaiton,Research And Optimization Of The Devices Based On Sorted Semiconducting Single-walled Carbon Nanotubes

Due to its unique geometry and rich electronic structure,semiconducting single-walled carbon nanotubes are widely used in various fields,especially in the fields of electricity and optoelectronics,and the prospects are promising.In general,uncontrolled growth of carbon nanotubes gets a mixture of metallic and semiconducting,the ratio of which should theoretically be 1:2.The presence of metallic tubes not only affects the electrical properties of the transistors based on semiconducting tubes,but also quenches exciton in the semiconducting tube,which makes them useless in other fields.Therefore,the metallic one must be excluded in practical applications.In this dissertation,the selective dispersion,a method of post-treatment,was used and the experimental conditions were optimized.The separated materials were utilized for the subsequent construction of electrical and photovoltaic devices.Finally,we use carbon tube regeneration with the original carbon nanotubes as a template to repair defects and extend their length to improve the performance of carbon nanotube devices.In terms of carbon nanotubes separation,this work selected one of the most efficient separation methods,namely,selective dispersion,with carbazolyl homopolymer,poly[9-(1-octylonoyl)-9H-carbazole-2,7-diyl](PCz),to separate the carbon nanotubes prepared by arc discharge method.With the help of high-power ultrasonication and high-speed centrifugation,we obtained a monodisperse solution of semiconducting carbon nanotubes with a purity of 99.9%by checking and optimizing the experimental conditions,and the concentration is acceptable.The thin film transistors were constructed and film formation has good electrical properties,and then the polymer is removed by washing during filtration and annealing,and the performance of the device can be greatly improved.Polymers can affect the properties of carbon nanotube devices,but the addition of carbon nanotubes can improve the performance of polymer transistor devices.Polymer thin film transistors have been plagued by poor interchain conduction of charge.In this dissertation,the close combine of?-?stacking between carbon nanotubes and polymers makes carbon nanotubes link polymer chains to improve their performance.In the case of PDPP-TT and PPy TDPP-BT,the mobility of hole(?_h)and electron(?_e)are both improved by 3 to 5 times,and the increase value is stable and uniform.The S₁₁ absorption of the semiconducting carbon nanotubes locates in the near-infrared region,so they can be used to fabricate the infrared photodetector,but the large exciton binding energy makes it hard.This dissertation adopted?-graphdiyne with conjugated system and suitable energy levels to assist the dissociation of photogenerated excitons in carbon nanotubes.The full-channel response detector was gotten with responsivity(R_V)of 0.4 m A·W^-1 and Detectivity(D*)of 5×10⁶cm Hz^1/2·W^-1,its response time is less than 1 ms.The semiconducting carbon nanotubes separated from the solution phase has a large number of defects and the length is very short.That means the carrier scattering in the device is severe,and the contact between the tubes also degrades the device performance.In this dissertation,a prospect that the regeneration through microwave heating was employed to improve the structure of semiconducting carbon nanotubes is shown.The preliminary result shows when the regeneration was done in the carbon nanotubes film,the on-off ratio of the devices increased from 5.1×10³ to 1.2×10⁴,and the current increased from 3.3?A to nearly 10?A.Raman spectrum showed that the G/D ratio increased from 8.1 to 12.4.This shows that the structure of carbon nanotubes is improved as well.