OLED DISPLAY DEVICE HAVING SOME OF THE PIXELS CONTAINING TWO DIODES WITH ORGANIC LAYERS OF DIFFERENT THICKNESS

摘要

A display comprises an array of organic light emitting diode (OLED) pixels, at least some of the pixels comprising a first (3) and a further diode (4) connected in parallel to a drive current. The first diode (3) has a larger area than the further diode (4), and the further diode (4) has a thinner active organic layer than the first diode (3), such that the further diode (4) has a greater drive current density in use than the first diode (3). The further diode ages faster than the first diode because it is driven harder. As it ages, the conductivity of the further diode decreases, and so more current passes through the first diode. The light emitted by the first diode therefore decreases at a slower rate than in the absence of the further diode, improving lifetime and reducing image burn-in at a cost of a small reduction in the initial efficiency of the display.