In OLED displays, screen pixels are composed of three different colored subpixels—red, green and blue—that light up at different intensities to create different colors. However, the Subpixels that emit blue light are the least stable and can be susceptible to screen "burn-in' which can discolor the screen and ruin viewing quality. An OLED is built like a sandwich, with organic semiconductor layers between two electrodes. This is especially a problem with blue light and reduces both the OLED efficiency