LG Display's Ultra-AMOLED displays were announced in August 2011, and were adopted by a single phone - the 2011 Optimus Sol. LG never revealed any details about those displays, besides saying that they include new technology that behaves better under sunlight compared to normal AMOLED displays - offering a 'two-fold advanced reflection rate'.
As we said, the only phone that adopted an Ultra-AMOLED display was the Optimus Sol. It had a 3.8" WVGA display and featured a Dark UI which conserved battery by 20%-30% (according to LG).
A short while after announcing their Ultra AMOLED displays, LG Display decided to stop making small-sized AMOLED panels, focusing instead on OLED TVs and plastic-based Flexible OLEDs.
When LG returned to the small-sized OLED market, they stopped using the Ultra AMOLED brand and started using the pOLED brand (p stands for plastic as these new flexible OLEDs are made on plastic films).