Study On The Self-assembly Film Of Optical Material Br₄Py And The Life Test Of LED

Under the guidance of national policies,LED lighting sources have achieved the development trend of marketization,intelligence and standardization around the goal of the 13th five year plan.It has been considered as the most valuable new light source in the 21st century.To enhance led reliability,improve LED luminous efficiency and extend LED life will gradually lead the accelerated development of the whole semiconductor industry.In this paper,the reliability of LED lighting devices is studied by the combination of test and simulation calculation.According to the LED reliability test,the type of accelerated life test of LED lighting devices is determined to predict the actual life of LED.Because tetrabromopyrene can be used to prepare carbazole compounds,the LED devices made of this kind of materials have good photoelectric properties,and have good application prospects in the field of electroluminescent devices.Therefore,the research on the structure and stability of tetrabromopyrene molecular self-assembled film on Au(111)surface is helpful to prepare LED devices with stable structure and excellent performance.The main work is as follows:1.Determine the reliability index of LED,including the main failure mode,failure analysis method,reliability test and optical material stability.In order to enhance the reliability of the test,accelerate the LED life detection process and reduce the test error,the type of life test is finally determined as constant stress accelerated life test,the life distribution model is Weibull life distribution,and the accelerated model is Arrhenius and peck accelerated model.2.Pyrene fluorescent materials and their synthesis and luminescent properties were studied.As an intermediate of optical materials,pyrene compounds have high light efficiency and high temperature resistance,which can delay the aging of optical materials.Taking 1,3,6,8-Br₄Py as an example,the atomic structure of self-assembled monolayers of Br₄Py on Au(111)surface has been studied by first principles.The results are as follows:Six monolayers of 1,3,6,8-Br₄Py were constructed by using the structural parameters of Au(111)surface,and their structural parameters and binding energy were optimized.Finally,two stable monolayers were obtained.The structural parameters were a=1.193 nm,b=0.958 nm,?=77°and a=1.549 nm,b=1.491nm,?=90°,which were in good agreement with the literature.Two stable molecular films were adsorbed on the surface of Au(111).The optimized adsorption height was0.40 nm,and the average transfer charge of each molecule was 0.24 e V.3.The life prediction of LED is studied.The life test is carried out under different stress modes of high temperature and high humidity.The life of LED under normal environment temperature and humidity is calculated by using optical test system and test data,thus a set of accelerated life test and detection system is obtained.The 1000 hour test results show that:after the aging test of three groups of test samples under different stress,the actual life of the products obtained by the acceleration model is not much different,which verifies the feasibility of this acceleration test;changing a single stress,temperature or humidity,the difference of the characteristic life of the products is relatively large,which shows that the temperature and humidity have a great impact on the life of lighting products At the same time,increase the temperature and humidity,the product aging speed is the fastest,and the impact on the product life is the largest,so strengthening heat dissipation and moisture-proof measures can effectively improve the life of lighting products.According to the calculation results,it is calculated that the life of the LED under normal environment temperature and humidity is about 93000 hours,the life value marked on the market is 100000 hours,and the error is about 7000 hours.Within the allowable range of error,the feasibility of the test is proved again,and the life of the LED can be predicted practically.This paper innovates the life detection method of LED lighting products,reduces the time of routine life detection of products,increases the accuracy of test results,and helps to standardize the LED life detection standard and the market's marking of life value of lighting products.