Printed Thin Film Transistors And Photoelectrical Characteristics Based On Polymer-Wrapped Monochiral(9,8)Carbon Nanotubes

Compared with the currently used semiconducting single-walled carbon nanotube(sc-SWCNTs)materials containing a variety of chirality sc-SWCNTs(such as conjugated organic compounds sorted sc-SWCNTs from arc discharge SWCNTs),mono-chiral(9,8)SWCNT has a certain band gap,relatively small diameter(that is,the relatively large band gap).Thus,much more excellent electrical properties of(9,8)SWCNTs thin film transistors(TFTs)such as extremely high on/off ratios,excellent device-to-device uniformity etc.,will be developed.Importantly,on/off ratios of theses electronic devices will not be obviously reduced with the increase of V_DS.Therefore,it is of great significance for the development of the next generation of carbon-based electronic devices to carry out the research of mono-chiral carbon nanotube devices.This thesis includes the following three parts:(1)Separation of mono-chiral(9,8)SWCNTs.The results show that[N,N'-bis(2-octyldodecyl)-isoindigo-co-(9,9-dioctylfluorenyl-2,7-diyl)](PFIID)had the capability to selectively wrap(9,8)SWCNTs from the raw SWCNT powers and the concentrations of mono-chiral(9,8)SWCNT inks could be tuned by adjusting the mass ratios of PFIIDs to raw SWCNT powers.The absorbance of S₁₁in absorption spectrum is as high as1.6 which demonstrate that SWCNT ink is rich in mono-chiral(9,8)SWCNTs.The selective wrapping mechanism was investigated with the aid of the molecular dynamic simulation.(2)Fabrication of mono-chiral(9,8)SWCNT TFTs.It is found that the performance of(9,8)SWCNT TFTs is seriously deteriorated by improper environment humidity during the ink deposition.To achieve better performance of SWCNT TFTs,it should be carried out under low humidity conditions when the drop casting process is employed.However,(9,8)SWCNT TFTs with excellent electrical characteristics can be obtained under any humidity conditions when using aerosol jet printing.It is attributed that(9,8)SWCNT inks are protected by nitrogen gas atmosphere during aerosol jet printing and deposition process and can prevent water and oxygen entering(9,8)SWCNT inks,facilitating the formation of strong interfacial bonding between(9,8)SWCNTs and substrates which resulted in the high efficient immobilizing(9,8)SWCNTs in substrates.Furthermore,the effects of the types of rinsing solvents,printing times and the concentrations of(9,8)SWCNT inks on the performance of printed(9,8)SWCNT TFTs are systematically investigated.For example,For example,excess polymers in the carbon nanotube films can be higher-efficiently removed when using the mixture of toluene and tetrahydrofuran(THF)as a cleaning solvent with the volume ratio of2:1.Better performance SWCNT TFTs with on/off ratio of 10⁸and mobility of?6cm²V^-1s^-1are successfully achieved after optimizing printing sc-SWCNT ink concentrations and printing times.Furthermore,no obvious variation of the on/off ratio of the device was observed with the drain-source voltage(V_DS)of-0.2,-0.5,and-1 V,respectively.To further improve the mobility of printed(9,8)SWCNT TFTs as well as keeping high on/off ratio(more than 10⁷),a novel ink in which mono-chiral(9,8)SWCNT ink was mixed with multi-chirality SWCNTs with larger diameter(P2)in a certain proportion.Interestingly,the mobility can reach 18 cm²V^-1s^-1,and on/off ratio of the SWCNT TFT devices are higher than10⁷,In addition,I_offincrease only slightly due to the addition of large-diameter sc-SWCNTs.(3)The(9,8)SWCNT phototransistor is constructed using lightly p-doped silicon as the bottom gate,and the photoelectric neuromorphic characteristics,photoelectric storage and storage,and logic functions were demonstrated under the stimulation of pulsed light and voltage.Furthermore,its performance including photoelectric neuromorphic characteristics,photoelectric storage and logic functions can be further improved after a layer of rhodamine B film in device channels was spin-coated.