A carbon nano-tube based photoelectric device includes a substrate and a carbon nanotube (CNT) over the substrate. The CNT comprises a first end and a second end, wherein the CNT has a CNT work function. A high work-function electrode over the substrate is in electric contact with the first end of the CNT. The high work-function electrode has a first work function higher than the CNT work function. A low work-function electrode over the substrate is in electric contact with the second end of the CNT. The low work-function electrode has a second work function lower than the CNT work function. The CNT can form a conductive channel between the high work-function electrode and the low work-function electrode. The carbon nano-tube based photoelectric device also includes a dielectric material is in contact with a side surface of the CNT and a conductive material in contact with the dielectric material.