In order to accurately acquire the life time information for the organic light emitting diode (OLED), an experiment based on the normal stress life test was carried out to gain the data for the luminance degradation tests. The luminance degradation model of OLED was established based on the Weibull function and the least square method. Combined with luminance degradation data, Weibull parameters were estimated, the qualitative and the quantitative relationship between the initial luminance and the OLED life was obtained, and the life estimation of the product was achieved. Numerical results show that the test scheme is feasible, the luminance degradation model proves to be reliable for the OLED life estimation, and the fitting accuracy is very high by comparison with the test data fluctuation. Moreover, the real life time of the OLED is measured, which can verify the validity of the assumptions used in accelerated life test methods and provide manufacturers and customers with significant guidelines.
In order to obtain reliability information for a white organic light-emitting diode (OLED), two constant and one step stress tests were conducted with its working current increased. The Weibull function was applied to describe the OLED life distribution, and the maximum likelihood estimation (MLE) and its iterative flow chart were used to calculate shape and scale parameters. Furthermore, the accelerated life equation was determined using the least squares method, a Kolmogorov-Smirnov test was performed to assess if the white OLED life follows a Weibull distribution, and self-developed software was used to predict the average and the median lifetimes of the OLED. The numerical results indicate that white OLED life conforms to a Weibull distribution, and that the accelerated life equation completely satisfies the inverse power law. The estimated life of a white OLED may provide significant guidelines for its manufacturers and customers.
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