An image sensor device is disclosed. The image sensor device comprises a substrate having a pixel region and at least one integrated circuit in the substrate of the pixel region. A photodiode is disposed on the substrate of the pixel region, comprising a lower electrode, a transparent upper electrode and a photoelectric conversion layer. The lower electrode is disposed on the substrate and is electrically connected to the integrated circuit. The photoelectric conversion layer is disposed on the lower electrode and has a submicron structure therein. The transparent upper electrode is disposed on the photoelectric conversion layer.