Finally, we compare the photodetection performance of our WS2/graphene heterostructure with other 2D vdW devices operating at telecom wavelengths. Notably, most results are located at the lower right-hand corner, reflecting a trade-off between responsivity and response time. In contrast, our WS2/graphene heterostructure with ultrafast hot carrier cooling and long electron circulation simultaneously possesses 3 ps intrinsic response time and 0.26 A/W responsivity while the WS2/graphene/WSe2 heterostructure exhibits a 1.71 ns extrinsic response time and 0.18 A/W responsivity, which are among one of the best performances (Figure ).