A photodetector, a driving method thereof, a display panel and a display device are disclosed in the field of display technology. The photodetector includes photosensitive element, a voltage divider, a switch circuitry and a detection transistor. The photosensitive element and the voltage divider are connected in series between two power terminals. The gate of the detection transistor is connected to a first voltage dividing node between the photosensitive element and the voltage divider. Therefore, when the resistance of the photosensitive element becomes smaller under illumination, the voltage of the first voltage dividing node correspondingly rises, and the detection transistor is turned on and may output a current to a read line under the driving of a DC power terminal. The magnitude of the current is determined by the magnitude of the voltage of the first voltage dividing node. Since the current output by the detection transistor under the driving of the DC power terminal is large, the influence of the leakage current of the detection transistor on the output current may be negligible, thereby effectively improving the accuracy of fingerprint identification based on the output current.