Self-powered and fast photodetector based on graphene/MoSe2/Au heterojunction

Abstract Two-dimensional (2D) materials have been demonstrated to be ideal candidates to design high performance photodetector owing to their novel optoelectronic features. However, large number of such simple photodetectors are photoconductive, which need external voltage to work effectively. In this paper, we proposed a kind of self-powered photodetector composed of semi-metallic graphene, semiconducting MoSe 2 and Au to generate two asymmetric contacts because these three materials owns different work functions. On one hand, the open-circuit voltage between MoSe 2 and Au enables the device to achieve self-powered photodetection with the high responsivity of 89.5 mA/W and specific detectivity of 2.24 × 10 10 jones. On the other hand, because of the ohmic contact between MoSe 2 and graphene, electrons can be transferred rapidly from MoSe 2 to graphene, leading to a short response time of only 9.6 ms. In addition, this photodetector possesses broader spectrum detection from 450 nm to 900 nm compared with the one made by MoS 2 as it owns much narrower bandgap. Our work offers a new approach for optoelectronic device design with low power consumption but high responsivity.