It does not have a backlight. E-ink can't use a backlight because it reflects light, rather than transmitting it. It can be used outdoors, because it is reflective. In fact sunlight is one of the best sources of light for modern E-Ink screens.
The Pearl E-Ink film is more or less like the Vizplex E-Ink film used in the earlier Kindles, except that it has more contrast. See E Ink announces next generation display platform