You manufacture OLED panels as thin slices of a sandwiched block. The sandwich is interleaved layers of:
1. Red/Blue terminal
2. Red OLED layers
3. thin insulator
4. Green/Red terminal
5. Green OLED layers
6. thin insulator
7. Blue/Green terminal
8. Blue OLED layers
9. thin insulator
you make a sandwich block of these layers, and then you slice it into thin panels. This thin slice panel is glued to the inside of a glass or plastic screen.
You display one color at a time. For example, to display red, you apply positive voltage to the Red/Blue terminal and ground the Green/Red terminal. This voltage is just under the threshold required to jump the thin insulative gap.
A microwave phased array produces a raster scanning beam by driving the transmitter elements at slightly different frequencies. The beam is polarized perpendicular to the stack so it will cause electrons to jump through the LED layers within the illuminated spot. By modulating the amplitude of the signal, the brightness of the pixel is modulated.
This display is something like a CRT display with a color wheel. However, the switching between Red, Green, and Blue is done electronically and can be done at a very high rate.
Unlike a CRT display, no vacuum tube is required so you can get large displays without excessive weight and cost. To make the display more compact, you can use a mirror or multiple microwave arrays.