According to a report from Japan's Nikkei Asian Review, Sharp will build an OLED production line at Foxconn's factory in Zhengzhou (northern China). The investment in this new fab will total around 100 billion yen (about $865 million) and production will begin in 2019. Sharp is specifically aiming to supply screens for Apple's future iPhones.
In October 2016 Sharp announced that it will invest $570 million to build OLED pilot lines in Osaka and in the Mie Prefecture. The pilot lines will begin OLED production in the summer of 2018. It was later reported that Sharp is considering to establish those lines in China instead - so it may be that this new Zhengzhou fab is actually the one reported in October.
Sharp's Korean competitors, LGD and SDC are not too worried, it seems - as they estimate that Sharp will not be able to compete with their OLED panels by at least 2020.