The invention discloses a PIN device, a manufacturing method thereof, a photosensitive assembly and a display device, and the PIN device comprises a lower electrode, a first doping layer, an intrinsiclayer, a second doping layer and an upper electrode, which are arranged in sequence; the second doping layer comprises a body part and an electric field isolation part which are arranged on the samelayer, wherein the electric field isolation part at least partially surrounds the body part so as to isolate an electric field formed on the side wall of the PIN device. In the embodiment of the invention, the electric field isolation part which at least partially surrounds the body part and is included in the second doping layer can isolate the electric field formed on the side wall of the PIN device, so that the dark current increase caused by the side wall damage of the PIN device is reduced, and the switching ratio and the performance of the PIN device are improved.