Display panel, display module, display device and brightness detection method

The invention discloses a display panel, a display module, a display device and a brightness detection method, the display panel comprises a display area and a peripheral area surrounding the display area, the peripheral area is provided with at least one photosensitive array, and the photosensitive array comprises at least one first photosensitive transistor and a plurality of second photosensitive transistors; the first photosensitive transistor is provided with a light blocking member used for blocking ambient light from irradiating the first photosensitive transistor. The second photosensitive transistor is provided with first color resistors used for transmitting part of ambient light to irradiate the second photosensitive transistor, and the first color resistors comprise at least two colors, so that a brightness determining unit determines the type of the ambient light according to the detection quantity of the second photosensitive transistor corresponding to the first color resistors with different c