NOVELTY - The photovoltaic electrochromic device comprises a transparent non-conductive substrate, a semi-transparent thin-film solar cell substrate comprising a transparent substrate and thin-film solar cells, an output switch layout coupled to the thin-film solar cells to control a current output from the thin-film solar cells, an electrochromic solution disposed between the transparent non-conductive substrate and the semi-transparent thin-film solar cell substrate, a reflective layer deposited on the transparent non-conductive substrate to form a mirror surface, and thin-film transistors.    USE - Used as photovoltaic electrochromic device such as a surface confined thin-film electrochromic device and a solution-type electrochromic device.    ADVANTAGE - The photovoltaic electrochromic device has high stability and high transmittance with less driving voltage, controls its current output using an additional output switch layout coupled with the thin-film solar cells, and automatically adjusts the colors of electrochromic windows to reduce indoor heat, based on indoor and outdoor illumination differences without any additional power supply.    DETAILED DESCRIPTION - The photovoltaic electrochromic device, comprises a transparent non-conductive substrate, a semi-transparent thin-film solar cell substrate comprising a transparent substrate and thin-film solar cells, an output switch layout coupled to the thin-film solar cells to control a current output from the thin-film solar cells, an electrochromic solution disposed between the transparent non-conductive substrate and the semi-transparent thin-film solar cell substrate, a reflective layer deposited on the transparent non-conductive substrate to form a mirror surface, and thin-film transistors for actively controlling the thin-film solar cells. An anode (300) and a cathode (310) of each of the thin-film solar cells serve as an anode and a cathode of the photovoltaic electrochromic device. The thin-film solar cells are arranged in array and/or in stripe, and are connected in parallel or series with the output switch layout, which is connected with a direct current/alternating current inverter to convert a current provided by the thin-film solar cells into general electricity and connected with a direct current charge storage device to store a direct current provided by the thin-film solar cells. The electrochromic solution comprises a redox-type of a cathodic electrochromic material and/or an anodic electrochromic material, a solvent and alkali metal salt. A redox voltage of the electrochromic solution is smaller than 3V. The thin-film solar cell substrate has a superstrate structure or a substrate structure. The transparent non-conductive substrate and transparent substrate of the semi-transparent thin-film solar cell substrate comprise glass, plastic or flexible substrate. The thin-film solar cells comprise silicon thin-film solar cells, copper indium gallium diselenide thin-film solar cells or cadmium telluride thin film solar cells. Each of the thin-film solar cells comprises a semiconductor stacked layer between the anode and cathode and passivation layers formed on sidewalls of the semiconductor stacked layer.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic top view of a photovoltaic electrochromic device.    Anode (300)    Cathode. (310)