To clarify, if the display is showing a white image will it heat up less in any measurable way compared to if it’s off and just showing black?
To clarify, if the display is showing a white image will it heat up less in any measurable way compared to if it’s off and just showing black?
No, and not because the effect is in any way small.
It is because a phone screen producing white light, looks white because it is actively generating white looking light. Compared to white paint, which looks white not because it generates its own light, but reflects other light, these are two different mechanisms for making things look ‘white’.
Your phone has a brightness setting, to keep ‘white’ the exact same shade of white despite whatever viewing condition you have. A white paint does not, and as a result, looks different depending on the amount of light in the room.
So in your hypothetical, a white phone screen won’t reflect less light as you presuppose - it’ll generate more heat internally - unless you cover the screen with white paint.
What about LCD? Switching the state of a cell results in mechanical changes, which might influence how much sunlight it absorbs (even if it’s minuscule compared to the heat generated by the backlight)
LCDs are designed to filter out extremely specific types of light, and in a specific direction.
It’s true that the changing optical properties of each crystal could affect the albedo, but whether white or black is more effective is beyond my knowledge. It might even be neither, but green instead.