Conventional photodetectors are subject to a trade-off between speed and responsivity. In photoconductive devices it is desirable for the responsivity to create gain via long lifetimes of the minority carriers, but this action simultaneously invokes long response times. Here, the so-called bulk photovoltaic effect (BPVE) can be advantageous, which is a nonlinear optical process that occurs in non-centrosymmetric materials, creating an anomalous current. spontaneous electronic polarization to separate charge carriers to result in theoretically high photoelectric conversion efficiencies. Potential candidates for its exploitation are the rhombohedral 3R-phase of many TMDCs that naturally possess an out-of-plane polarization (Figure ) or heterostructures where the required breaking of the inversion symmetry is created at the interface. In a graphene/3R-MoS2/graphene heterostructure, this concept demonstrated an intrinsic response time of 2 ps, indicating a high photodetection bandwidth comparable to graphene. Moreover, the conversion efficiency for the BPVE is related to the free path length (l0), which refers to the non-thermalized carrier transit length before they descend to the bottom of the conductive band. Due to the small thickness of the graphene/3R-MoS2/graphene heterostructure, the vertical charge carrier collection distance is smaller than l0, resulting in a responsivity of 70 mA/W -1 and EQE of 16 %, which is large considering the fast speed of the detector. 42