Applied strain introduces significant changes in the carbon–carbon bond of graphene and thereby forms electronic superlattices. The electron/phonon coupling and existence of pseudogauge fields within these superlattices render unique electronic and magnetism properties. However, the interfacial interactions between strained and pristine graphene have rarely been studied. Herein, we report a prominent increase in photocurrent at the interface between pristine graphene and the strain-induced superlattice (i.e., the graphene wrinkle). The photocurrent distribution indicates a large increase in the bending lattice of graphene. These results demonstrate that the photocurrent enhancement is due to the difference in the Seebeck coefficient between pristine graphene and deformed superlattices, resulting in a significant increase in the photo­thermo­electric effect at the interface.

Black phosphorus (BP) is a typical two-dimensional (2D) layered material with strong in-plane anisotropy and large birefringence, making it possible to manipulate the light field with atomically controlled devices for various optoelectronic and photonic applicationsfor instance, atomic thickness waveplates. The twist angle in twisted black phosphorus (TBP) can be presented as a new tunable dimension to control BP's optical anisotropy. Here, we report a large and tunable optical rotation effect in TBP, the result of regulating the twist angle and BP thickness. To accurately study the optical rotation and the impact of the twist angle, we developed a new method to prepare TBP. A lab-made polarimeter microscope was used to visualize the optical rotation mapping of TBP. A large polarization-plane rotation (PORA) of 0.49°per atomic layer was observed from an air/BP/ SiO 2 /Si Fabry−Peŕot cavity at 600 nm, an order of magnitude higher than the PORA of 0.05°per atomic layer reported earlier. For the same thickness, the PORA of TBP can be tuned from 0.48°to 7.75°based on the twist angle from 0°to 90°. Our work provides an efficient method to investigate the anisotropy of 2D materials and their heterojunctions. TBP could help us design novel optical and optoelectronic devices such as tunable nanoscale polarization controllers.

Strain engineering is the most effective method to break the symmetry of the graphene lattice and achieve graphene band gap tunability. However, a critical strain (>20%) is required to open the graphene band gap, and it is very difficult to achieve such a large strain. This limits the development of experimental research and optoelectronic devices based on graphene strain. In this work, we report a method for preparing large-strain graphene superlattices via surface energy engineering. The maximum strain of the curved lattice could reach 50%. In particular, our pioneering work reports the behavior of an ultrafast (as short as 6 ps) photoresponse in a strained folded graphene superlattice. The photocurrent map shows a large increase (up to 10 2 ) of the photoresponsivity in the tensile graphene lattice, which is generated by the interaction between the strained and pristine graphene. Through Raman spectroscopy, Kelvin probe force microscopy, and high-resolution transmission electron microscopy, we demonstrate that the ultrathreshold strain in the graphene bends triggers the opening of the graphene band gap and results in a unique photovoltaic effect. This work deepens the understanding of the strain-induced change of the photoelectrical properties of graphene and proves the potential of strained graphene as a platform for the generation of novel highspeed, miniaturized graphene-based photodetectors.

In the mol­ecule of the title compound, C17H13N3O2, the naphthyl ring system and the pyridine ring form a dihedral angle of 12.2 (3)°. An intra­molecular O—H⋯N hydrogen bond generates a six-membered ring with an S(6) ring motif. This also contributes to the relative overall near planarity of the mol­ecule [r.m.s. deviation of all 22 non-H atoms = 0.107 (5) Å]. In the crystal, mol­ecules are linked through inter­molecular N—H⋯N hydrogen bonds, forming chains along the a axis.

The optical signals (such as Raman scattering, absorption, reflection) of van der Waals heterostructures (vdWHs) are very important for structure analysis and the application of optoelectronic devices. However, there is...