The US PTO published a new patent application from Apple that describes an OLED display with a built-in fingerprint reader. The idea is that integrating Near Infrared (NIR) emitters and detectors between the OLED subpixels will enable a much thinner design compared to separate display and detector layers. This also means that there is no need to have a separate reader in the home button as in current iPhones.
The Fraunhofer Institute has demonstrated bi-directional OLED microdisplays back in 2012 that are based on a similar idea - embedding photo detectors (in the visible light range, in that case) within the OLED sub pixels. The latest prototype unveiled in 2015 supports SVGA resolution and a hi-res image sensor. The bi-directional displays are available for sampling.
In past years Apple has been filing many OLED patents - mostly dealing with flexible OLEDs for mobile devices. In June 2012 for example, Apple filed for a new patent that describes a wraparound flexible transparent display that enables new form factors. In March 2013 Apple filed a patent that describes an option to include multiple transparent displays, overlaid on top of one another. Apple's latest patent turns a flexible OLED display into a speaker membrane.
According to some reports, Apple is in discussions with Samsung Display to supply flexible OLED panels for future iPhones and with Japan's JOLED for iPad OLEDs. Apple first-gen Watch uses a flexible OLED supplied by LG Display.