Your smartphone's camera is made up by a number of elements and one of them is its aperture. A camera's aperture is simply a hole through the optics stack through which light travels before it hits the image plane. The size of that hole determines how much light is admitted, and thus, how much light will reach the image, so a narrower aperture (higher F values, like F5.0) will result in a relatively darker image than a wider aperture (lower F values, like F1.8). That is, if all else is equal.
Unlike DSLRs, however, nearly every smartphone on the planet has its aperture fixed and you can't do anything about it. All smartphone have pretty wide apertures in comparison, too, because the cameras on our phones have tiny lenses and need all the light that they can get in order to produce acceptable results. That's why, as a rule, the wider the aperture, the better.
Of course, there's more to smartphone imaging than just aperture. For example, a wider aperture will result in a brighter photo only if all other things are equal. In reality, it's not uncommon for some phones with relatively narrower apertures to produce brighter and better overall results than their counterparts with wider apertures, so do keep that in mind.
We ranked the smartphones with the widest apertures for your convenience below. Check out who they are.
* Arranged in ascending order. Due to the large volume of devices with F2.0 lenses, we've skipped over a few.