Disclosed is an array substrate and a method for manufacturing the same and a display device. The array substrate comprises: a substrate; a first electrode layer formed on the substrate; a pixel defining layer formed on the first electrode layer and having an opening for exposing the first electrode layer; and an organic material functional layer formed on a region of the first electrode layer corresponding to the opening. The first electrode layer comprises: a first region located at a central portion of the first electrode layer; a second region located between a periphery of the first region and an inner side of the pixel defining layer, the second region being formed as a first arc structure protruding toward the substrate; and a third region located outside the second region and covered by the pixel defining layer. The thicknesses, at positions of respective films of the organic material functional layer in the display device, are uniform. Non-uniform brightness of the display device is avoided, improving display quality of images of the display device.