Bulk Photovoltaic Effect in Two-Dimensional Distorted MoTe<sub>2</sub>.

Aftab, Sikandar; Shehzad, Muhammad Arslan; Salman Ajmal, Hafiz Muhammad; Kabir, Fahmid; Iqbal, Muhammad Zahir; Al-Kahtani, Abdullah A · ACS Nano · 2023

basic_science · Level V

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Abstract

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<sub>2</sub>, caused by the phase transition and broken inversion symmetry in MoTe<sub>2</sub>. The phase transition from single-crystalline semiconducting 2H-MoTe<sub>2</sub> to semimetallic 1T'-MoTe<sub>2</sub> 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 <i>V</i><sub>OC</sub> = 16 mV and a positive signal of the <i>I</i><sub>SC</sub> = 60 μA (400 nm, 90.4 Wcm<sup>-2</sup>) in the absence of an external electric field. The maximum values of both <i>R</i> and EQE were found to be 98 mAW<sup>-1</sup> 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.