"Samsung will be the only supplier for the 2020 OLED-based iPhones with 5.4-inch and 6.7-inch display sizes. For the 6.1-inch display device, LG Display will be used, in addition to Samsung, to ensure consistent supply. It is likely that BOE will not be an Apple supplier in 2020.
Apple was testing BOE for a long time as potential OLED supplier, but it is not included in the list in 2020 because of slow progress in development and production. Apple is not taking any risk with the iPhone production. This is allowing Samsung to consolidate its position as leading the next wave OLED development thanks to its capability to deliver high-quality displays and meet large production demand." – Karn Chauhan