A COA array substrate includes a base substrate, a TFT layer disposed on the base substrate, a pixel electrode layer and black matrixes disposed on the TFT layer, and a quantum dot color filter film disposed on the pixel electrode layer. The quantum dot color filter film is formed through electrochemical deposition applied to a mixture of quantum dots dispersed in electrolyte including chitosan. Through application of a voltage, chitosan brings the quantum dots to deposit on the TFT layer.