A method of designing a fixed format emissive display is described using a computing device having a processor and a memory, the display comprising an array of emissive pixel elements, each pixel element comprising at least two sub-pixel elements made of different materials. The method comprises selecting areas of the at least two sub-pixel elements so that each pixel element displays white at a predetermined white point within a certain tolerance over a lifetime of the pixel, and such that the lifetimes of the sub-pixel areas are within a predetermined tolerance of each other.A display having sub-pixel elements optimized so that each pixel element displays white at a predetermined white point within a certain tolerance over a lifetime of the pixel, and such that the lifetimes of the sub-pixel areas are within a predetermined tolerance of each other is also described.