Does black wallpaper save smartphone battery power

Are they saving or not?

It all depends on the type of smartphone display, and specifically on the backlight used in it. In all kinds of TFTs, including TN and IPS, there is a common constant backlight, that is, each pixel is always highlighted regardless of its color. Accordingly, even if a pixel shows black, it still glows. With these types of displays, setting black wallpaper will not help, but dimming or automatic (adaptive) brightness adjustment will save battery power.

OLED displays work very differently. There is no general constant illumination in them, each pixel glows by itself. From the physics course, you know that black is the absence of light, and therefore in OLED displays, the pixel is simply turned off to display black. When the pixel is off, it does not consume power. Accordingly, the more black pixels on an OLED display, the less battery power it uses.

The Always On Display mode, which Samsung and LG are so actively promoting in their products, is just a combination of a black display and a minimum brightness, which allows you to constantly display basic information on the screen without noticeable damage to the battery charge.

How to find out the display type of a smartphone

You will have to connect all your skills in searching for information on the Web and google a query like "[smartphone model] display type."

OLED displays are already quite popular now. They are used in almost all Samsung models and many smartphones from other manufacturers. Remarkably, even Apple plans to move all future iPhones to OLED displays by 2019.

How to make and install black wallpaper

In any sane graphics editor, create a-p.webp

For example, if the display resolution is 720 × 1,280 pixels and you are using a standard five-screen launcher, then the wallpaper resolution should be 1,440 × 1,280 pixels. If the display is 1,080 × 1,920, then the wallpaper should be 2,160 × 1,920 pixels.

Copy the created graphic file to the smartphone memory and set it as wallpaper.