According to Japanese newspaper Nikkei, the switch to OLED is taking place with the iPhone 7s in 2017, one to two years earlier than expected. Previous speculation had Apple holding off on making the switch until the launch of the Apple iPhone 8 in 2018, and super analyst Ming-Chi Kuo expects Apple to hold the course until 2019 at the earliest.
Apple could use an OLED panel to improve the battery life on the iPhone, and at the same time, making the switch will allow Apple to produce a thinner handset. One fresh report says that Apple is close to inking a $12 billion contract with LG and Samsung for OLED panels. Talk about such a deal first appeared just before the curtain fell on 2015.
source: Nikkei (translated) via TechRadar