Bulk Photovoltaic Effect in Two-Dimensional Distorted MoTe2

In future solar cell technologies, the thermodynamic Shockley-Queisser limit for solar-to-current conversion in traditional p–n junctions could potentially be overcome with a bulk photovoltaic effect by creating an inversion broken symmetry in piezoelectric or ferroelectric materials. Here, we unveiled mechanical distortion-induced bulk photovoltaic behavior in a two-dimensional (2D) material, MoTe 2, caused by the phase transition and broken inversion symmetry in MoTe 2 . The phase transition from single-crystalline semiconducting 2H-MoTe 2 to semimetallic 1T′-MoTe 2 was confirmed using X-ray photoelectron spectroscopy (XPS). We used a micrometer-scale system to measure the absorption of energy, which reduced from 800 to 63 meV during phase transformation from hexagonal to distorted octahedral and revealed a smaller bandgap semimetallic behavior. Experimentally, a large bulk photovoltaic response is anticipated with the maximum photovoltage V OC = 16 mV and a positive signal of the I SC = 60 μA (400 nm, 90.4 Wcm –2 ) in the absence of an external electric field. The maximum values of both R and EQE were found to be 98 mAW –1 and 30%, respectively. Our findings are distinctive features of the photocurrent responses caused by in-plane polarity and its potential from a wide pool of established TMD-based nanomaterials and a cutting-edge approach to optimize the efficiency in converting photons-to-electricity for power harvesting optoelectronics devices.