Abstract
Photosensing and energy harvesting based on exotic properties of quantum materials and new operation principles have great potential to break the fundamental performance limit of conventional photodetectors and solar cells. Weyl semimetals have demonstrated novel optoelectronic properties that promise potential applications in photodetection and energy harvesting arising from their gapless linear dispersion and Berry field enhanced nonlinear optical effect at the vicinity of Weyl nodes. In this work, we demonstrate robust photocurrent generation at the edge of Td-WTe2, a type-II Weyl semimetal, due to crystalline-symmetry breaking along certain crystal fracture directions and possibly enhanced by robust fermi-arc type surface states. This edge response is highly generic and arises universally in a wide class of quantum materials with similar crystal symmetries. The robust and generic edge current response provides a charge separation mechanism for photosensing and energy harvesting over broad wavelength range.
Highlights
Photosensing and energy harvesting based on exotic properties of quantum materials and new operation principles have great potential to break the fundamental performance limit of conventional photodetectors and solar cells
We experimentally show that the photo excited electron–hole pairs can be separated efficiently along certain edges due to the broken of C2v symmetry upon fracturing along certain crystallographic directions, which provides robust edge current response in Type-II Weyl semimetal WTe2 under normal incidence
Td-WTe2 with crystal structure shown in Fig. 1a is proposed as an inversion-symmetry breaking type-II Weyl semimetal[27]
Summary
Photosensing and energy harvesting based on exotic properties of quantum materials and new operation principles have great potential to break the fundamental performance limit of conventional photodetectors and solar cells. Efficient separation of photo-excited electron–hole pairs is an essential ingredient for various highly applicable fields such as photo sensing[1], solar energy harvesting[2] and photo catalysis[3] For this purpose, imbalanced momentum distribution of non-equilibrium photo-excited charge carriers, either from population imbalance or velocity imbalance in k-space, is required. The inversion symmetry breaking can naturally occur in some classes of crystals, which could lead to efficient charge separation of photo-excited carriers and result in shift current response[9] This phenomenon, which is often referred to as bulk photovoltaic effect (BPVE) or anomalous photovoltaic effect[10,11], is due to the fact that the real space position of electron shifts a little as the expected electron positions of the ground state and the excited state are slightly different after photoexcitation under homogenous photo illumination in non-centrosymmetric crystal. Type-II Weyl semimetals with C2v crystal point group, such as WTe2, MoTe2, and TaIrTe425,26, the second order nonlinear shift current response vanishes if light incidence direction is along the crystallographic ^c-axis[25]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
