Construction Of Electrochemiluminescent System Based On Deep Eutectic Solvents And Its Research Application In Electrochemiluminescent Devices

Traditional electrolyte solutions used in electrochemiluminescent devices are organic solvents or ionic liquids containing supporting electrolytes,and the flammability of organic solvents and toxicity of ionic liquids limit the application of their devices in luminescent displays.The deep eutectic solvents(DES)not only inherits the advantages of ionic liquids such as high designability and low volatility,but also has the characteristics of good biocompatibility,wide source,easy preparation and environmental friendliness,which has become a hot spot of attention for more and more scholars.Therefore,this thesis proposes the preparation of novel luminescent layers with deep eutectic solvents for the study of electrochemiluminescent devices,and the main work carried out is as follows:(1)In the first part of the work,ChCl-LA DES were prepared using choline chloride(ChCl)and lactic acid(LA)by mixing at a certain temperature,and used for the study of annihilation electrochemiluminescence of[Ru(bpy)3]2+.In ChCl-LA DES,[Ru(bpy)3]2+ can be oxidised to the stable[Ru(bpy)3]3+radical and reduced to the unstable[Ru(bpy)3]+radical.Furthermore,[Ru(bpy)3]3+is sufficiently stable on the time scale to react with[Ru(bpy)3]3+in ChCl-LA DES by potential scanning or potential pulsing,resulting in strong annihilation electrochemiluminescence.Further,a novel electrochemiluminescent device was constructed using a solution of[Ru(bpy)3]2+ in ChCl-LA DES as a liquid luminescent layer(ChCl-LA DES/[Ru(bpy)3]2+).The results show that the electrochemiluminescent device can emit orange-red light visible to the naked eye under the effect of a certain alternating voltage.(2)Based on the first part of the work,gel-state luminescent layers(ChCl-LA DES/CS/[Ru(bpy)3]2+)were prepared by mixing ChCl-LA DES,chitosan(CS)and[Ru(bpy)3][PF6]2,then used for the construction of electrochemiluminescent.devices.Gel-state luminescent layer showed that the components in the luminescent layer were highly compatible,forming a homogeneous conductive gel with an irregular microscopic pore structure on its surface.The electrochemiluminescent devices based on ChCl-LA DES/CS/[Ru(bpy)3]2+gel-state luminescence layer exhibit good luminescence display performance under the effect of specific alternating voltage,which is visible to the naked eye.(3)In the third part of the work,ChCl-EG DES was prepared by mixing choline chloride(ChCl)and ethylene glycol(EG)at a certain temperature to verify that trifluoroethanol has an enhancing effect on the coreactant electrochemiluminescence of[Ru(bpy)3]2+ with TPrA in this system.Afterwards,the polymer-gel state luminescent layer ChCl-EG DES/PAA/[Ru(bpy)3]2+ was prepared by combining[Ru(bpy)3][PF6]2,acrylic acid and ChCl-EG DES,and the gel-type electrochemiluminescent devices were prepared by using the gel-state luminescent layer.The characterization of the polymer gel layer shows that components are uniformly distributed,the surface microstructure is porous,and the overall electrical conductivity of the layer is excellent.The coreactant ECL of the devices prepared with the PDES/[Ru(bpy)3]2+ polymer gel layer is also visible to the naked eye,and the amount of cross-linker and trifluoroethanol incorporated affects the electrochemical luminescence of the devices.Further,the enhancement of the coreactant ECL of the devices under trifluoroethanol doping was achieved based on the enhancement of the electrochemiluminescence of[Ru(bpy)3]2+ by using trifluoroethanol in the deep eutectic solvents.