Controllably tuned infrared emissivity has attracted great interest for potential application in adaptive thermal camouflage. In this work, we report a flexible multilayer graphene based infrared device on a porous polyethylene membrane, where the infrared emissivity could be tuned by ionic liquid intercalation. The Fermi level of surface multilayer graphene shifts to a high energy level through ionic liquid intercalation, which blocks electronic transition below the Fermi level. Thus, the optical absorptivity/emissivity of graphene could be controlled by intercalation. Experimentally, the infrared emissivity of surface graphene was found to be tuned from 0.57 to 0.41 after ionic liquid intercalation. Meanwhile, the relative reflectivity R_v/R₀ of surface graphene increased from 1.0 to 1.15. The strong fluorescence background of Raman spectra, the upshift of the G peak (~23 cm⁻¹), and the decrease of sheet resistance confirmed the successful intercalation of ionic liquid into the graphene layers. This intercalation control of the infrared emissivity of graphene in this work displays a new way of building an effective thermal camouflage system.

The near-infrared (NIR) photoelectric properties of multilayer Bi₂O₂Se nanofilms were systematically studied in this paper. Multilayer Bi₂O₂Se nanofilms demonstrate a sensitive photo response to NIR, including a high photoresponsivity (~ 101 A/W), a quick response time (~ 30 ms), a high external quantum efficiency (~ 20,300%), and a high detection rate (1.9 × 10¹⁰ Jones). These results show that the device based on multilayer Bi₂O₂Se nanofilms might have great potentials for future applications in ultrafast, highly sensitive NIR optoelectronic devices.

With the packing density growing continuously in integrated electronic devices, sufficient heat dissipation becomes a serious challenge. Recently, dielectric materials with high thermal conductivity have brought insight into effective dissipation of waste heat in electronic devices to prevent them from overheating and guarantee the performance stability. Layered CrOCl, an anti-ferromagnetic insulator with low-symmetry crystal structure and atomic level flatness, might be a promising solution to the thermal challenge. Herein, we have systematically studied the thermal transport of suspended few-layer CrOCl flakes by micro-Raman thermometry. The CrOCl flakes exhibit high thermal conductivities along zigzag direction, from ∼ 392 ± 33 to ∼ 1,017 ± 46 W·m⁻¹·K⁻¹ with flake thickness from 2 to 50 nm. Besides, pronounced thickness-dependent thermal conductivity ratio (κ_ZZlκ_AR from ∼ 2.8 ± 0.24 to ∼ 4.3 ± 0.25) has been observed in the CrOCl flakes, attributed to the discrepancy of phonon dispersion and phonon surface scattering. As a demonstration to the heat sink application of layered CrOCl, we then investigate the energy dissipation in graphene devices on CrOCl, SiO₂ and hexagonal boron nitride (h-BN) substrates, respectively. The graphene device temperature rise on CrOCl is only 15.4% of that on SiO₂ and 30% on h-BN upon the same electric power density, indicating the efficient heat dissipation of graphene device on CrOCl. Our study provides new insights into two-dimentional (2D) dielectric material with high thermal conductivity and strong anisotropy for the application of thermal management in electronic devices.

Transition metal dichalcogenide based 2D/2D or 2D/3D van der Waals heterostructures exhibit superior properties for high-performance electronics, tunneling transistors, and catalysts. Here, we report on the fabrication of high quality 2D/3D MoS₂/MoO₂ heterostructures with an atomic clean interface by one-step chemical vapor deposition. Optical microscopy, atomic force microscopy, Raman spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy measurements reveal the high-quality of as-grown samples and the specific epitaxial relationship between MoS₂ and MoO₂: MoS₂[$\overline{1}\overline{1}$ 20]//MoO₂[001] and MoS₂[$\overline{1}$ 100]//MoO₂[201]. Photoluminescence and Kelvin probe force microscopy measurements combined with density functional theory calculations confirm the interfacial charge transfer from MoS₂ to the underlying MoO₂. Furthermore, MoO₂ induced in-plane anisotropy in MoS₂ was revealed using angle-resolved polarized Raman and photoluminescence spectroscopy with anisotropic ratios of 1.27 (Raman) and 1.29 (photoluminescence), respectively, which is most possibly attributed to anisotropic interfacial charge interactions. Our findings provide an excellent platform for the investigation on interfacial effects. Moreover, the in-plane anisotropy in MoS₂ induced by MoO₂ has expanded the application of isotropic MoS₂ in the polarization-dependent fields.