Atomic configuration controlled photocurrent in van der Waals homostructures

Abstract

Conventional photocurrents at a p–n junction depend on macroscopic built-in fields and are typically insensitive to the microscopic details of a crystal’s atomic configuration. Here we demonstrate how atomic configuration can control photocurrent in van der Waals (vdW) materials. In particular, we find bulk shift photocurrents (SPCs) can display a rich (atomic) configuration dependent phenomenology that range from contrasting SPC currents for different stacking arrangements in a vdW homostructure (e.g. AB vs BA stacking) to a strong light polarization dependence for SPC that align with crystallographic axes. Strikingly, we find that SPC in vdW homostructures can be directed by modest strain, yielding sizeable photocurrent magnitudes under unpolarized light irradiation and manifesting even in the absence of p–n junctions. These demonstrate that SPC are intimately linked to how the Bloch wavefunctions are embedded in real space, and enables a new macroscopic transport probe (photocurrent) of lattice-scale registration in vdW materials.

Shift-current response as a probe of quantum geometry and electron-electron interactions in twisted bilayer graphene

“…This is in agreement with previous results of Ref. [55] and [50] for TBG and gapped bilayer graphene respectively. We note however, that Ref.…”

“…[55] studies the frequency response in range 1-10meV and Ref. [50] considers a frequency of 100meV. Finally, our work for the first time shows how photoresponse can serve as a probe of electron-electron interactions in TBG pointing towards a novel experimental direction for the TBG field.…”

“…Specifically, the magnitude of such QG effects is sensitive to the change in average position of Bloch wavefunctions within the unit cell [17]. Previous works that studied shift current response in bilayer graphene and TMDs [34,[50][51][52][53] predicted a strong effect due to their non-zero Berry curvature profile.…”

Unveiling the Linear Photogalvanic Effect in a Two-Dimensional Organic Tin Halide Perovskite: (CH3)2NH2SnI3

“…Previous studies have elucidated that the strength of SPC response shares a close connection with the wavefunction asymmetry and the band characters of electronic states involved in photoexcitation. 9,10,15,17,18 With the shared relationship between BPVE and second harmonic generation (SHG), i.e., dependence on the broken inversion symmetry, perovskites with distorted structures and noncentrosymmetric space groups can induce LPGE. Indeed, with the shared structures between ferroelectric (FE) oxides and metal halide perovskites, LPGE has been observed in several perovskites including the organic−inorganic metal halide perovskites, e.g., the star material CH 3 NH 3 PbI 3 (MAPbI 3 ) mainly in its bulk structure using similar techniques.…”

“…Photocurrents induced by NLO processes have reinvigorated fundamental optics, for example, in optoelectronic devices such as NLO photodetectors, absorbers, and solar cells. One of these interesting NLO processes, the bulk photovoltaic effect (BPVE) produces a steady photocurrent from a single-phase homogeneous material and is touted as a probable alternative to the traditional photovoltaic mechanism based on p–n junctions. , In this mechanism, photocurrent generation occurs across an entire bulk material independent of Shockley–Queisser limitations imposed by materials’ bandgaps, − providing an avenue for high-efficiency photovoltaics. Recently, Hatada et al and Luo et al documented that the linear photogalvanic effect (LPGE)-induced photocurrent (shift photocurrent, SPC), the main component of BPVE is robust against crystal defects and impurities (internally and on the surface) and shows dissipationless and ultrafast response.…”