Characterization Of The Molecular Orientation Of Organic Materials Based On Angle-resolved Photoluminescence Spectroscopy

With the popularity of organic light-emitting diode(OLED)applications,the development of high-performance OLED devices has become an important topic in this field.The molecules of organic luminescent materials tend to be oriented,which will greatly affect the optical properties of the material and device,such as optical anisotropy.In practice,in order to improve the performance of OLED devices,it is necessary to precisely control the orientation of organic material molecules.Therefore,accurate measurement and characterization of the molecular orientation of organic materials is conducive to our optical simulation analysis and optimization design to improve the performance of materials and devices.At present,spectroscopic ellipsometers are commonly used to determine the molecular orientation of organic materials by measuring the anisotropic optical constants of materials.However,the measurement method is only applicable to pure material.In the doped material,the anisotropy caused by the orientation of the luminescent material is very weak,the spectroscopic ellipsometer is difficult to accurately characterize molecular orientation.Therefore,in order to deal with the problem of accurate measurement of molecular orientation of doped material in organic light-emitting devices,this paper proposes a method for measuring and characterizing organic molecular orientation based on angle-resolved spectroscopy,developed an angle-resolved photoluminescence measurement device,and established a forward optical model and reverse parameter reconstruction method to achieve accurate measurement and characterization of molecular orientation in doped luminescent film.In this paper,the forward luminescence calculation model of angle-resolved photoluminescence spectroscopy of organic luminescent materials is firstly established,and the theoretical method of reversely calculating the molecular orientation using angleresolved photoluminescence spectroscopy is proposed.The numerical simulation shows the model and method effectiveness and correctness.Then,the working principle and design scheme of the angle-resolved photoluminescence spectrometer were introduced,and the corresponding optical system and mechanical structure were designed.The angle-resolved photoluminescence spectrometry experimental device was set up to test its function and performance.Finally,the experimental device and the proposed theoretical method were used to verify the typical organic luminescent materials: by determining the molecular orientation of the typical randomly oriented material and comparing it with the ellipsometric measurement results,the proposed theoretical method and the correctness of the experimental device;by measuring the molecular orientation of the typical doped material system,the advantages of this method are demonstrated.The method for characterizing the orientation of organic molecules based on angleresolved photoluminescence spectroscopy,the constructed optical calculation model of angle-resolved photoluminescence spectroscopy and the experimental device for angleresolved photoluminescence spectroscopy,as well as the corresponding experimental results and discussions Luminescent materials and device performance control and structure optimization design device optimization provides theoretical guidance and experimental means,which is of great significance for improving the efficiency of organic light-emitting devices and developing high-performance OLED devices.