Application Of Micro-nano Device Based On Fully Transparent Ionic Gel And Study Of Its Flexible Properties

With the rapid development of the internet of things and consumer electronics in the past decade,the demand for high-performance,portable,and wearable electronic devices has driven the density upgrade of transistor integration.However,due to the tunnel effect,in the post-Moore era,significant efforts have been devoted to studying the materials and structures of devices to improve the performance of field-effect transistors.Ionic liquids,composed of anions and cations,are binary salts with high polarity and low melting points.They have played a considerable role in electrochemical devices,brake sensors,optical devices,catalysis,separation,lubricating materials,electrochemiluminescent materials,and drug delivery.Compared with traditional solid dielectrics,when ionic liquids are utilized as the gate dielectrics of electrical devices in the gate field-effect transistors,they have two levels of improvement in regulating the carrier concentration.However,the application of ionic liquids is limited by their liquid morphology.In order to maintain their original properties,adding polymers to the ionic liquids for the ionic liquid gels has become the mainstream solution.As an electrolyte,ion gels have become the focus of the transparent display,foldable screen,wearable communication devices,biological-integrated circuits,and robotic sensory skin because of their excellent physical stability,chemical stability,flexibility,lightweight,transparency,and many other characteristics.This thesis focuses on the preparation of ionic liquid gels,characterization of physical properties,application of micro-nano devices,and their performance stability on flexible substrates,and hopes to expand their applications in high-performance field-effect transistors and wearable electronic devices.The main research contents are as follows:（1）The ionic liquid gel film was prepared under a strict raw material ratio,and a step profiler measured the rotational speed-thickness dependence of the film to precisely control the thickness of the film.An optical absorption spectrometer tested the transmittance of the film,and the film almost reached 100%transmittance in the visible spectrum.Capacitor arrays based on ion gel were prepared.Their capacitance-frequency（C-f）characteristics were tested using a semiconductor tester,which was comparable to a pure ionic liquid,proving that the addition of polymers did not affect their capacitance characteristics.（2）Graphene was prepared by the mechanical exfoliation method and proved to be a single layer structure by the Raman test.Graphene field-effect transistors were prepared by EBL lithography and EBE evaporation equipment.The magnetic properties of graphene at low temperatures were tested,and the mobility and carrier concentration changes at different temperatures were counted.The transition between weak localization and antilocalization occurs in graphene at a low temperature.The ion gel film was covered in the channel region in the way of shearing.SiO₂ and ionic liquid gel film were used as gate dielectric layers,respectively,and the device’s transfer and output characteristic curves were measured.Ion gel improves the switching ratio and transconductance of the device.（3）Ionic liquid gel capacitors based on flexible substrates were fabricated,and the capacitance attenuation under different bending radii was tested as well.The minimum bending radius can reach1.88mm,and the strain can reach up to 3.3%.In order to explore the bending stability of the gel,the capacitance values after different bending times were tested.Experimental tests showed that thousands of times of bending had little effect on the capacitance of the gel,which shows that ion gel has great application prospects in flexibility and other aspects.