Give your gizmo the gift of sight
I have worked with OLEDs as displays, but am unaware of their application as an image sensor. I have heard of them being used to detect chemicals that cause them to change color or intensity that would be mesured by an image sensor looking at the OLED. http://www.ameslab.gov/files/FactSheet_OLED_FOUNDATION.pdf OLEDs are designed to emit light when a voltage is applied and it sounds like you want to use them in reverse - truning them into organic photodiodes to generate a voltage when light is applied to them. I am not an expert in this area, but am doubtful that this type of transduction is possible in some useful way with current OLED materials.