Disclosed is a substrate, comprising an underlayment, and a light-blocking member and a photosensitive sensing layer arranged on the underlayment. The photosensitive sensing layer comprises at least one photosensitive sensor unit for detecting a visible light signal, and the photosensitive sensing layer converts the visible light signal detected by the at least one photosensitive sensor unit into an electrical signal corresponding to the light intensity thereof. The light-blocking member blocks light rays at one side from radiating onto the photosensitive sensor unit. Also disclosed are a display panel and a display device.