A portable electronic device, such as a notebook computer, includes a base and a lid. The base or the lid includes a shell and a multilayer structure coating thereon. The multilayer structure includes an electrically conductive layer, an electro chromic layer, an electrolyte layer, an ion storage layer and an electrode layer stacked one on another in that order. The portable electronic device utilizes the electro chromic layer to change colors, thereby the color-change function of the portable electronic device is achieved. Additionally, the electrode layer contains a photo catalyst TiO.sub.2 that has deodorizing, antibacterial and self-cleaning functions.