A couple of weeks ago, at IDW 2016, AU Optronics introduced a new bi-directional foldable AMOLED display. This display can be bent both inwards and upwards, unlike previous foldable AMOLED prototypes which can only be bent in one direction.
AUO says that the AMOLED structure limits the flexibility, and to overcome this the company replaced the circular polarizer usually used with a thin (10um) color filter array (apparently this is an WRGB display). AUO also used specially-located TFT and TFE (encapsulation) layers that endure many folding cycles - AUO says that the display can be bent more than 1.2 million times in 4mm curvature radius. The entire display thickness is 100 um.