Design Of Organic Small Molecule Electrogenerated Chemiluminescence Devices And Their Performance Study

Electrogenerated chemiluminescence,also known as electrochemiluminescence（ECL）,is a chemiluminescence process triggered by an electrical signal,which is a redox reaction between excited radicals at an electrode under the action of a voltage to produce light emission.It has been developed rapidly in recent decades by cleverly combining electrochemical and chemiluminescence strategies,combining the advantages of high electrochemical controllability and low chemiluminescence background signal.The temporal and spatial control with long light emission makes ECL technology a very attractive and powerful sensing and imaging platform.In recent years,with the rise of materials science and the popularity of electrical technology,the design of ECL devices and the integration of new functions are more diverse than ever.For example,scientists have invented a variety of ECL devices based on the superior performance of ECL for point-of-care testing,cell microscopy imaging,electrochemical imaging,and wearable sensors,among others.Despite the extensive reports on ECL devices,the luminescence performance such as luminescence stability,intensity,and device lifetime of electrochemiluminescence is still severely challenged by the limited number of luminescent active molecules,which requires comprehensive design solutions and further efforts.Based on the above research background,the research in this thesis is divided into the following sections around the design and mechanistic study of organic small molecule electrochemiluminescent devices:（1）By electrodepositing the semiconductor material Bi VO₄ on the surface of the ITO electrode as a photoanode,combined with the photochemical properties of semiconductor materials,a new light-induced electrochemiluminescence device was designed,which realized light-induced electrochemiluminescence（P-ECL）without external power supply.Experiments show that under the condition of ultraviolet excitation light,it can cause DPA to undergo electrochemiluminescence reaction.Moreover,through the study of the electrochemical performance test of devices and non-wire-connected devices,we found that the electron-hole separation efficiency of semiconductors is enhanced due to the structure of the device,thereby further enhancing the electrochemiluminescence intensity of small organic molecules.Furthermore,stable yellow upconversion P-ECLD has been achieved by replacing the ECL active molecule,and as a beneficial combination of photoelectrochemistry and electrochemiluminescence based on metal oxide semiconductor materials,we believe that P-ECL provides a new basis for the development of new detection equipment and imaging strategies.（2）The multi-color display electrochemiluminescence device with excellent luminescence performance was prepared by optimizing the driving strategy.In order to improve the stability of luminous intensity,we greatly improve the electrochemiluminescence lifetime and intensity by using low-frequency pulse drive.Compared with conventional ECL displays driven by continuous voltage,blue and yellow ECL displays under the low-frequency pulse drive strategy have a 2-8 times higher luminous intensity under the same voltage input,and the luminous life is significantly enhanced.In this study,blue,green,and yellow emitted liquid ECL displays have been successfully demonstrated.ECL display was achieved using erythromene,tris（2-phenylpyriridine）iridium,and 9,10-diphenylanthracene,corresponding to red,green,and blue light emission,respectively.Optimized ECL displays display long-life,high-intensity emissions at a 5:1duty cycle of low-frequency pulses.In addition,through the analysis of molecular luminescence spectroscopy under pulse drive,the main luminescence mechanisms of three molecules under pulse drive were verified.In particular,the ECL test of luminol system was designed to verify the trilinear-trilinear annihilation luminescence mechanism of erygnonene electrochemiluminescence.In addition,by proportional mixing of luminescent active materials and by adjusting the pulse duty cycle,a simple and controllable multi-color display is realized.