Only midrange to high-end devices. Cheaper ones (which are very common especially in poorer countries) still use simpler LCD/LED screens.
LCD screens have a backlight that’s always on and consumes the same amount of power regardless of what’s on the screen. OLEDs don’t have a backlight; when the screen is dark, the pixels in that area are actually turned off.
Not all phones; just ones with OLED screens.
CRTs will also save power as they have to shoot fewer phosphors, but that’s not really relevant today.
Don’t pretty much all phones have OLED screens?
These guys say it’s about 50%.
Only midrange to high-end devices. Cheaper ones (which are very common especially in poorer countries) still use simpler LCD/LED screens.
LCD screens have a backlight that’s always on and consumes the same amount of power regardless of what’s on the screen. OLEDs don’t have a backlight; when the screen is dark, the pixels in that area are actually turned off.