A photodetector and a manufacture method thereof, a touch substrate and a display panel are provided. The photodetector includes: a substrate; a polysilicon layer on the substrate including a first doped region and a second doped region; a transparent conductive film covering the first doped region of the polysilicon layer; and a metal electrode on the second doped region of the polysilicon layer. The conductive film, the metal electrode and the polysilicon layer constitute a photosensitive device.