Is using a display panel as a light sensor conceivable?
Individual LEDs can be used as light sensors: they behave like photodiodes. 
OLEDs are potentially capable of behaving like this as well (they're also semiconductors), but I can't find reports of anyone having tried it. It's probably extremely inefficient.

LCDs cannot: they operate by applying a field to twist the crystals, and there's no photosensitivity in this process.

Note that unless you optically focus and project an image onto the screen, you won't get a usable image even if you do manage to read out of an OLED screen. You'll just get the average of the incident light.