Array substrate and manufacturing method thereof, display panel and display device

A method for manufacturing an array substrate comprising:

• forming a first via hole for connecting a second transparent electrically conductive layer and a gate line layer, a second via hole for connecting a first transparent electrically conductive layer and the second transparent electrically conductive layer, and a third via hole for connecting the second transparent electrically conductive layer and a source/drain electrode layer on a base substrate through patterning process;
• performing a filling process on the first via hole, the second via hole and the third via hole during a pattern of second transparent electrically conductive layer is being formed, such that each of the first via hole, the second via hole and the third via hole are filled with a filler, and a top surface of the filler in each of the first via hole, the second via hole and the third via hole is in the same horizontal plane as portions of the second transparent electrically conductive layer surrounding the respective via holes.