Self-powered tunable photodetection via flexoelectric engineering of single-phase 2HMoS2

Abstract

Two-dimensional (2D) molybdenum disulfide (MoS₂) has shown considerable potential for photodetection, yet existing MoS₂-based photodetectors require either external voltage bias or complex heterojunctions. In this work, we present a new device concept based on flexoelectric engineering of bulk photovoltaic effect (BPVE) of 2HMoS₂, simplifying the device configuration considerably while enhancing its self-powered photodetection performance. By introducing a strain gradient in the suspended 2HMoS₂, we break its inversion symmetry, resulting in BPVE in the otherwise centrosymmetric system. The significant flexoelectric polarization induced also facilitates efficient photocarrier separation, leading to a 41-fold enhancement in short-circuit photocurrent under a strain gradient of $0.95{\mathrm{\mu m}}^{-1}$. Furthermore, the flexoelectric-engineered photodetector can be dynamically tuned via air pressure, enabling multilevel photoconductance and achieving a responsivity of 191 mA/W. This performance surpasses existing self-powered MoS₂-based photodetectors reported in literature, offering a strategy for enhanced photodetection.