The G5 uses an LCD display, but Cho says that LG could start using OLED displays for its flagship phones by the second half of 2017. LG will not purchase panels from Samsung Display, but it is waiting for LG Display to start producing OLEDs for mobile phones.
LG Display already produces OLED displays, in fact, but in a very limited capacity. LGD has a Gen-4.5 fab (14,000 monthly substrates) that produces flexible (plastic-based) OLEDs. LG currently mostly makes small flexible OLEDs for wearables (such as Apple's Watch and LG's own Watch Urbane 2). LG makes a single handset flexible OLED, the curved 5.5" FHD panel adopted in the company's own G Flex 2 - but this was never really a mass produced device.
LGD announced plans to build a Gen-6 (1500x1850 mm) flexible OLED fab in a $900 million investment. The new E5 line will be located at LGD's Gumi Plant and will have a capacity of 7,500 monthly substrates - or 1.5 million 5.5" panels. The new fab is scheduled to begin mass production in the first half of 2017. Cho probably considers the new Gen-6 fab when he aims to release phones later in 2017 that use these OLEDs.
Earlier reports suggested that LG Display indeed aims to enter the mobile phone market with its flexible OLEDs, and actually hopes to do so in 2016 - but in that case the company will have to start with lower-volume phones (reportedly LGD is in talks with Chinese phone makers Vivo and Oppo)