Apple's iPhone X sales were lower than expected, which resulted in a reduction of OLED display orders from SDC (from an estimated 40 million in Q1 2018 to 20 million). Several reports also suggested that Apple may decide to only introduce one new OLED iPhone model in 2018 (the larger 6.5" one, with panels made by LGD).
One of these reports came from Taiwan's Digitimes, but a new report from Digitimes suggests that Apple does plan to upgrade its OLED iPhone X in 2018. According to Digitimes, Apple will introduce a slightly larger 5.9" OLED model. In total Apple will buy 110-130 OLED panels in 2018, for all three OLED models (the 2017 iPhone X, the 2018 5.9" iPhone XI and the larger 6.5" OLED iPhone XI plus).