Pixel unit, array substrate, and display device, and their fabrication methods are provided. The disclosed pixel unit can include: a transistor, including a drain electrode; a pixel electrode, including a first bottom conductive layer in contact with a surface of the drain electrode and a metal layer; and a planarization layer, formed on the transistor and the first bottom conductive layer. The metal layer is electrically connected to the first bottom conductive layer through a via-hole in the planarization layer.