Impact of Long-Term Stress on the Light Output of a WRGB AMOLED Display

Abstract

This paper describes how long-term use impacts the light output of a commercial 55” WRGB AMOLED display with InGaZnO TFT backplane. This covers effects which are known by the terms “aging”, “image-sticking,” and “burn-in.” The focus is on three different observations: permanent change in light output as a function of time, permanent screen burn-in, and permanent shift in color point. From this work it can be concluded that state-of-the-art OLED displays still suffer from light output instability under prolonged stress. The results suggest that the permanent change in light output can be explained by the combination of three different phenomena: a decrease in efficiency of the OLEDs as a function of time for active subpixels, a positive threshold voltage shift of the driving transistor for active subpixels, and a negative threshold voltage shift of the driving transistor for inactive subpixels, if they are illuminated and/or kept at high temperature. To our knowledge, this is the first work that describes and quantifies the permanent change in light output of a commercial WRGB OLED panel with InGaZnO TFT backplane. It sheds light on which effects occur and can be a valuable tool, both in the design and optimization of OLED panels and in the determining the circumstances under which this technology may be applicable.