Boosting Bulk Photovoltaic Effect in 3R-MoS2 by Edge Semimetal Contact

Bulk photovoltaic effect (BPVE) has traditionally been observed in oxide materials with non-centrosymmetric structures. However, these materials exhibited cell efficiencies too low for practical use. In recent years, larger BPVE coefficients have been reported in two-dimensional (2D) layers and stacks with asymmetry-induced spontaneous polarization. We now report a significant breakthrough in enhancing the BPVE in 3R-MoS₂ by utilizing edge contact (EC) geometry with bismuth semimetal electrodes. EC induces a pronounced tensile strain in the 3R-MoS₂ and allows complete access to the in-plane polarization from the underlying layers exposed to light. This approach results in over a 100-fold increase in BPVE-generated photocurrent. Specifically, the EC device demonstrated a significantly larger BPVE compared to the top-conatced device, with noticeable improvements in both <i>I</i>_sc and <i>V</i>_oc, surpassing previously reported values. Additionally, by creating a 3R-MoS₂/WSe₂ heterojunction, we show that BPVE can be constructively coupled with the conventional photovoltaic effect (PVE) in the designed devices, marking a significant advancement toward practical applications.