A display panel includes a plurality of pixels disposed on a first panel substrate of first and second panel substrates that face each other and cooperate to display an image. The second panel substrate includes a base substrate, a read-out line, a first insulating layer, a scan line, a switching device, and a light sensor. The read-out line is disposed on the base substrate and extended in a direction. The first insulating layer is disposed on the read-out line. The scan line is extended to cross the read-out line and disposed on the first insulating layer. The switching device includes a first electrode connected to the scan line, a second electrode connected to a read-out line, and a third electrode spaced apart from the second electrode. The light sensor is structured to selectively detect lights of predetermined wavelengths and connected to the third electrode of the switching device.