That could actually work. They already make low persistence OLED displays for use in VR, where the screen stays black for most of the frame and a bright bar of

That could actually work. They already make low persistence OLED displays for use in VR, where the screen stays black for most of the frame and a bright bar of image rolls down the screen. The iPhone can already operate in this mode. I assume there is a display brightness penalty, but the image quality from the camera should be fine as long as it gets more than half the frame collecting light.