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Two-dimensional (2D) non-layered materials, along with their unique surface properties, offer intriguing prospects for sensing applications. Introducing mechanical degrees of freedom is expected to enrich the sensing performances of 2D non-layered devices, such as high frequency, high tunability, and large dynamic range, which could lead to new types of high performance nanosensors. Here, we demonstrate 2D non-layered nanomechanical resonant sensors based on β-In₂S₃, where the devices exhibit robust nanomechanical vibrations up to the very high frequency (VHF) band. We show that such device can operate as pressure sensor with broad range (from 10⁻³ Torr to atmospheric pressure), high linearity (with a nonlinearity factor as low as 0.0071), and fast response (with an intrinsic response time less than 1 μs). We further unveil the frequency scaling law in these β-In₂S₃ nanomechanical sensors and successfully extract both the Young's modulus and pretension for the crystal. Our work paves the way towards future wafer-scale design and integrated sensors based on 2D non-layered materials.

Plasmonic hot carrier engineering holds great promise for advanced infrared optoelectronic devices. The process of hot carrier transfer has the potential to surpass the spectral limitations of semiconductors, enabling detection of sub-bandgap infrared photons. By harvesting hot carriers prior to thermalization, energy dissipation is minimized, leading to highly efficient photoelectric conversion. Distinguished from conventional band-edge carriers, the ultrafast interfacial transfer and ballistic transport of hot carriers present unprecedented opportunities for high-speed photoelectric conversion. However, a complete description on the underlying mechanism of hot-carrier infrared optoelectronic device is still lacking, and the utilization of this strategy for tailoring infrared response is in its early stages. This review aims to provide a comprehensive overview of the generation, transfer and transport dynamics of hot carriers. Basic principles of hot-carrier conversion in heterostructures are discussed in detail. In addition, progresses of two-dimensional (2D) infrared hot-carrier optoelectronic devices are summarized, with a specific emphasis on photodetectors, solar cells, light-emitting devices and novel functionalities through hot-carrier engineering. Furthermore, challenges and prospects of hot-carrier device towards infrared applications are highlighted.

Enabling pressure sensors with high resolution and a broad detection range is of paramount importance yet challenging due to the limitations of each known sensing method. Overlying different sensing mechanisms to achieve complementary functions is a promising approach, but it often leads to increased device thickness, crosstalk signals and complex signal channel management. Herein, we present a dual-functional conformable pressure sensor that adopts a Janus thin film layout, enabling simultaneous piezoelectric and triboelectric signal detection capabilities between just one electrode pair, showing a most compact device configuration. Notably, despite its thin thickness (~80 μm for a packaged device), it exhibits a broad-range detection capability with high signal resolution and fast response time, demonstrating a distinct signal-relay characteristic corresponding to piezoelectricity and triboelectricity. Despite the slimness and simple structure, it shows an impressive signal resolution of 0.93 V·kPa⁻¹ in the range of 0.1–140 kPa and 0.05 V·kPa⁻¹ in the range of 140–380 kPa. Moreover, the device fabrication can be combined with the kirigami method to improve fitting to joint surfaces. This work introduces an innovative paradigm for designing advanced pressure sensing mechanisms, enabling a single device that can meet diverse application scenarios through its simplicity, slim layout, conformable, and self-powered characteristics to adapt to multiple scenarios.

Visible light-based human–machine interactive media is capable of transmitting electrical readouts to machines and providing intuitive feedback to users simultaneously. Currently, many inorganic mechanoluminescent (ML) materials-based interactive media, typically ZnS-loaded phosphors (ZLPs), have been successfully demonstrated. However, organic ML materials-based solutions were rarely exploited despite their huge merits of strong structural modification, abundant luminescence property, low cost, easy preparation, and so on. Here, we propose a novel interactive tactile display (ITD) based on organic ML materials (Cz-A6-dye) and triboelectric nanogenerator, with ultra-brightness (130% enhancement) and ultra-low threshold pressure (57% reduction) as compared to ZLPs. The proposed ITD achieves the conversion of weak mechanical stimuli into visible light and electrical signals simultaneously, without extra power supplies. Furthermore, the relationship between the luminous performance of organic ML materials and mechanical force is quantified, benefiting from the uniform ML layer prepared. Enabled by convolutional neural networks, the high-accuracy recognition (97.1%) for handwriting and identity of users is realized at the same time. Thus, the ITD has great potential for intelligent wearable electronics and classified military applications.

The rapid development of emerging technologies observed in recent years, such as artificial intelligence, machine learning, mobile internet, big data, cloud computing, and the Internet of Everything, are generating escalating demands for expanding the capacity density, and speed in next-generation optical communications. This poses a significant challenge to existing communication techniques. Within this context, the integration of near-infrared broadband, tunable, and high-gain luminescent materials into silicon optical circuits or fiber architectures to transmit and modulate light shows enormous potential for advancing next-generation communication techniques. Here, this review provides an overview of the recent breakthroughs in near-infrared luminescent epitaxial/colloidal quantum dots, and metal-active-center-doped materials for broadband optical amplifiers and tunable lasers. We also expound on efforts to enhance the bandwidth and gain of these materials-based amplifiers and lasers, exploring the challenges associate with developing ultra-broadband and high-speed optical communication systems. Additionally, the potential applications in Fifth Generation Fixed Networks, integration with 5G and 6G wireless networks, compensation for current Si electronic based CMOS for high computing capability, and the prospects of these light sources for next-generation optoelectronic devices are discussed.

The simultaneous detection of multiple stimuli, such as pressure and temperature, has long been a persistent challenge for developing electronic skin (e-skin) to emulate the functionality of human skin. Meanwhile, the demand for integrated power supply units is an additional pressing concern to achieve its lightweightness and flexibility. Herein, we propose a self-powered dual temperature–pressure (SPDM) sensor, which utilizes a compressible ionic gel electrolyte driven by the potential difference between MXene and Al electrodes. The SPDM sensor exhibits a rapid and timely response to changes in pressure-induced deformation, while exhibiting a slow and hysteretic response to temperature variations. These distinct response characteristics enable the differentiation of current signals generated by different stimuli through machine learning, resulting in an impressive accuracy rate of 99.1%. Furthermore, the developed SPDM sensor exhibits a wide pressure detection range of 0–800 kPa and a broad temperature detection range of 5–75°C, encompassing the environmental conditions encountered in daily human life. The dual-mode coupled strategy by machine learning provides an effective approach for temperature and pressure detection and discrimination, showcasing its potential applications in wearable electronics, intelligent robots, human–machine interactions, and so on.

Photonic and plasmonic hybrid nanostructures are the key solution for integrated nanophotonic circuits with ultracompact size but relative low loss. However, the poor tunability and modulability of conventional waveguides makes them cumbersome for optical multiplexing. Here we make use of two-dimensional molecular crystal, α-Sb₂O₃ as a dielectric waveguide via total internal reflection, which shows polarization-sensitive modulation of the propagating beams due to its large polarization mode dispersion. Both experiments and simulations are performed to verify such concept. These Sb₂O₃ nanoflakes can be coupled with plasmonic nanowires to form nanophotonic beam splitters and routers which can be easily modulated by changing the polarization of the incidence. It thus provides a robust, exploitable and tunable platform for on-chip nanophotonics.

Prussian blue analogs (PBAs) are potential contestants for aqueous Mg-ion batteries (AMIBs) on account of their high discharge voltage and three-dimensional open frameworks. However, the low capacity arising from single reaction site severely restricts PBAs' practical applications in high-energy-density AMIBs. Here, an organic acid co-coordination combined with etching method is reported to fabricate defect-rich potassium-free copper hexacyanoferrate with structural water on carbon nanotube fiber (D-CuHCF@CNTF). Benefiting from the high-valence-state reactive sites, arrayed structure and defect effect, the well-designed D-CuHCF@CNTF exhibits an extraordinary reversible capacity of 146.6 mAh g⁻¹ with two-electron reaction, nearly close to its theoretical capacity. It is interesting to unlock the reaction mechanism of the Fe²⁺/Fe³⁺ and Cu⁺/Cu²⁺ redox couples via x-ray photoelectron spectroscopy. Furthermore, density functional theory calculations reveal that Fe and Cu in potassium-free D-CuHCF participate in charge transfer during the Mg²⁺ insertion/extraction process. As a proof-of-concept demonstration, a rocking-chair fiber-shaped AMIBs was constructed via coupling with the NaTi₂(PO₄)₃/CNTF anode, achieving high energy density and impressive mechanical flexibility. This work provides new possibilities to develop potassium-free PBAs with dual-active sites as high-capacity cathodes for wearable AMIBs.

Layered two-dimensional (2D) materials have garnered marvelous attention in diverse fields, including sensors, capacitors, nanocomposites and transistors, owing to their distinctive structural morphologies and superior physicochemical properties. Recently, layered quasi-2D materials, especially layered bismuth oxyselenide (Bi₂O₂Se), are of particular interest, because of their different interlayer interactions from other layered 2D materials. On this basis, this material offers richer and more intriguing physics, including high electron mobility, sizeable bandgap, and remarkable thermal and chemical durability, rendering it an utterly prospective contender for use in advanced electronic and optoelectronic applications. Herein, this article reviews the recent advances related with Bi₂O₂Se. Initially, its structural characterization, band structure, and basic properties are briefly introduced. Further, the synthetic strategies for the preparation of Bi₂O₂Se are presented. Furthermore, the diverse applications of Bi₂O₂Se in the field of electronics and optoelectronics, photocatalytic, solar cells and sensing were summarized in detail. Ultimately, the challenges and future perspectives of Bi₂O₂Se are included.

Modulation of light underpins a central part of modern optoelectronics. Conventional optical modulators based on refractive-index and absorption variation in the presence of an electric field serve as the workhorse for diverse photonic technologies. However, these approaches based on electro-refraction or electro-absorption effect impose limitations on frequency converting and signal amplification. Lanthanide-activated phosphors offer a promising platform for nonlinear frequency conversion with an abundant spectrum. Here, we propose a novel approach to achieve frequency conversion and digital modulation of light signal by coupling lanthanide luminescence with an electrically responsive ferroelectric host. The technological benefits of such paradigm-shifting solution are highlighted by demonstrating a quasi-continuous and enhancement of the lanthanide luminescence. The ability to locally manipulate light emission can convert digital information signals into visible waveforms, and visualize electrical logic and arithmetic operations. The proof-of-concept device exhibits perspectives for developing light-compatible logic functions. These results pave the way to design more controllable lanthanide photonics with desired opto-electronic coupling.