It does have an OLED screen!!!
If you wnat to get more battery life out of the phone: the first thing to do is swich off "Automatic" screen brightness. then set the brightness to about 15%. right down near the bottom of the slider. only turn it up if you are in bright daylight - or working on something which needs the extra brightness.
Install a widget to easily get to the brightness settings from a home page to make it
easier.
Before I did this my screen used up to 90% of my battery - and typically about 75 - 80%. now it uses about 40 - 50%, and I can normally get from one end of the day to the other, with several hours browsing, emailing listening to internet audio streams &c &c.