Twisted stacking of van der Waals materials with moiré superlattices offers a new way to tailor their physical properties via engineering of the crystal symmetry. Unlike well-studied twisted bilayers, little is known about the overall symmetry and symmetry-driven physical properties of continuously supertwisted multilayer structures. Here, using polarization-resolved second harmonic generation (SHG) microscopy, we report threefold (C₃) rotational symmetry breaking in supertwisted WS₂ spirals grown on non-Euclidean surfaces, contrasting the intact symmetry of individual monolayers. This symmetry breaking is attributed to a geometrical magnifying effect in which small relative strain between adjacent twisted layers (heterostrain), verified by Raman spectroscopy and multiphysics simulations, generates significant distortion in the moiré pattern. Density-functional theory calculations can explain the C₃ symmetry breaking and unusual SHG response by the interlayer wave function coupling. These findings thus pave the way for further developments in the so-called "3D twistronics".

Two-dimensional transition metal dichalcogenides have demonstrated potential for advanced electrical and optoelectronic applications. For these applications, it is necessary to modify their electrical or optoelectronic properties. Doping is one of the most prevalent techniques to modify the band structure of semiconductor materials. Herein, we report the p-type doping effect on few-layer and multi-layer MoS₂ that are selectively decorated with Ag nanoparticles via laser-assisted direct photoexcitation of MoS₂ exposed in AgNO₃ solution. This method can control the doping level by varying the duration of the laser irradiation, which is confirmed by the observed gradual rise of MoS₂ device channel resistance and photoluminescence spectra enhancement. This study demonstrated a simple, controllable, and selective doping technique using laser-assisted photo-reduction.

Piezochromic luminescent (PCL) materials have attracted extensive research interest due to their potential applications in mechanosensors, ink-free printing, optical data storage, optoelectronic devices, etc. However, there have been few reports on the near-infrared (NIR) piezochromic luminescence of π-conjugated organic materials under external hydrostatic pressure. Herein, we report the design and preparation of five pressure-sensitive AIEgens: TPAM, BTPAM, FTPAM, MTPAM and MOTPAM. These materials exhibit piezochromic luminescence behaviors, whereby their emission colors exhibit significant blue-shifts upon gentle manual grinding due to the phase transition from the crystalline to the amorphous state. With an increase in applied hydrostatic pressure, significant emission red-shifts (up to >200 nm) toward the NIR region were observed with the modification of substituents, attributed to the enhanced intermolecular π–π interactions. The unsubstituted TPAM did not exhibit any red-shifted emission due to the synergistic effect between enhanced intermolecular interactions and molecular configuration deformation during the compression process.