Preparation Of Flexible ACEL Device Based On Imidazole Chloride Iongels And Study On Antifreeze And Water Retention Properties

With the rapid iteration and update of intelligent wearable devices and people’s higher demand for intelligence and portability,wearable devices with both intelligent display and excellent flexibility have become a major problem in this field.Flexible alternating current electroluminescence（ACEL）devices,whose electrodes are mainly composed of conductive polymers,have good photoelectric and tensile properties at the same time,and have great development potential in the field of smart wearable.Ionic gel,as a new conductive polymer,combines the advantages of gel polymer and ionic liquid（IL）.It not only has high ionic conductivity,but also has excellent flexibility,which is very suitable for flexible ACEL devices.However,ionic gel still has some shortcomings,such as high operating voltage,unable to work normally in natural environment（low temperature,dry）.Therefore,it is of great significance to study flexible ACEL devices with frost resistance and water retention properties.In order to solve the above problems,this paper takes polyvinyl alcohol（PVA）as the main body of ionic gel network,adding 1-ethyl-3-methylimidazole chloride（Emimim Cl）as conductive material and plasticizer,using boric acid（BA）as chemical crosslinking agent,using freeze-thawing method to prepare ionic gel electrode.Glycerol（Gly）,ethylene glycol（EG）and calcium dichloride（Ca Cl₂）were introduced into the system to make it have the properties of antifreeze and water retention.A flexible ACEL device was assembled by coating PDMS coated with Zn S:Cu powder as electroluminescence layer.Combined with low temperature freezing box,electric blast drying box and hygrometer test devices such as frost resistance and water retention performance.The component structure and photoelectric properties of the device were analyzed by luminance meter,digital multimeter,Fourier transform infrared spectroscopy（FTIR）,thermogravimetric analysis（TGA）,ultraviolet visible spectrophotometer（Uv-Vis）and microconfocal spectrometer.The effects of the types and contents of each component and the experimental parameters on the device performance were studied,and finally the flexible electroluminescence device with the best performance was prepared.The main research contents are as follows:（1）By introducing Emim Cl ionic liquid into PVA hydrogel and using boric acid as crosslinking agent,ionic gel films were prepared by freeze-thaw method.The interaction of each component and its influence on the properties of ionic gel were studied.It was found that Emim Cl is not only the conductive material of ionic gel,but also effectively increases the flexibility of ionic gel.At the same time,the crosslinking of boryl ester bond in the main chain of PVA makes the ion gel have a dynamic and reversible network structure.When the content of Emim Cl in ionic gel is 80%,the tensile property is 230%and the self-healing property is91%.When the content of Emim Cl is 100%,the ionic conductivity is 3.4×10^-3S/cm,and the light transmittance is up to 94%（film thickness is 1mm）.（2）Use the excellent properties of ion gels,Flexible ACEL devices were assembled by rolling coating method with PDMS coated with Zn S:Cu powder as intermediate electroluminescence layer and ion gel as electrodes at both ends.It is found that the devices have a sandwich structure and are closely connected to each other.The Emim Cl content of the device is proportional to the electrical conductivity and photoelectric performance,and the luminescence performance of the device is 50 V,1700 Hz,114 cd/m² when the Emim Cl content is 80%.In addition,the luminescence intensity of the device is still 83.3%when the device is stretched twice.After 800 times of cyclic stretching（200%）,the luminescence intensity of the device can still maintain 74.6%of the initial value.（3）By adding glycerol（Gly）,ethylene glycol（EG）and calcium dichchloride（Ca Cl₂）into ionic gel,a flexible ACEL device with anti-freezing and water-retaining properties was prepared.The effects of different antifreeze water-retaining agents on the ionic gel system and the mechanism of the overall performance of the device were studied.It was found that the addition of antifreeze water-retaining agents significantly improved the antifreeze water-retaining performance of the device.When the volume ratio of glycerol（Gly）and ethylene glycol（EG）was greater than 30%and the content of calcium dichchloride（Ca Cl₂）was 2.2-4.4Mol/L,The device can work normally at-18℃.When the volume ratio of glycerol（Gly）to ethylene glycol（EG）is greater than 50%and the content of calcium dichloride（Ca Cl₂）is greater than 3.3Mol/L,the performance can be maintained for up to 31 days under natural environment（T=25～28°C,RH=55～85%）.However,the addition of antifreeze water-retaining agent can only slow down the water loss rate in the device,but can not completely prevent the water loss in extreme environment（T=80℃,RH=9%）.