A method for operating a photosensitive device is provided. At first, the photosensitive device is provided, which comprising a photo sensor circuit and a photo sensor, where the photo sensor is located above and electrically coupled with the photo sensor circuit, and where the photo sensor comprises a bottom electrode; a photosensitive layer located on the bottom electrode; and a transparent electrode located on the photosensitive layer. Then, a first electrical potential is supplied to the transparent electrode, and a second electrical potential is supplied to the bottom electrode, where the first electrical potential is greater than the second electrical potential.