Very small but should be good for some Arduino projects ... only the pixels that are on use electricity. This makes OLED technology very efficient; also, the way these types of OLEDs are built allows ...

But QD-OLED and WOLED may not be the only choices we have for very long. There are plenty of types of OLED. One of them is called PHOLED (Phosphorescent OLED), which uses phosphorescent materials ...