Colossal switchable photocurrents in topological Janus transition metal dichalcogenides

Abstract Nonlinear optical properties, such as bulk photovoltaic effects, possess great potential in energy harvesting, photodetection, rectification, etc. To enable efficient light–current conversion, materials with strong photo-responsivity are highly desirable. In this work, we predict that monolayer Janus transition metal dichalcogenides (JTMDs) the 1T′ phase colossal nonlinear photoconductivity owing to their topological band mixing, inversion symmetry breaking, and small electronic bandgap. JTMDs have inverted bandgaps on order of 10 meV exceptionally responsive light terahertz (THz) range. By first-principles calculations, reveal shift current (SC) conductivity large 2300 nm μA V −2 , equivalent a 2800 mA/W. The circular (CC) is ∼10 4 . These remarkable photo-responsivities indicate can serve photodetectors THz We also find external stimuli in-plane strain out-of-plane electric field induce transitions SC abruptly flip directions. abrupt change photocurrent be used characterize has applications 2D optomechanics optoelectronics.