Infrared (IR) detection is vital for various military and civilian applications. Recent research has highlighted the potential of two-dimensional (2D) topological semimetals in IR detection due to their distinctive advantages, including van der Waals (vdW) stacking, gapless electronic structure, and Van Hove singularities in the electronic density of states. However, challenges such as large-scale patterning, poor photoresponsivity, and high dark current of photodetectors based on 2D topological semimetals significantly impede their wider applications in low-energy photon sensing. Here, we demonstrate the in situ fabrication of PtSe2/Ge Schottky junction by directly depositing 2D PtSe2 films with a vertical layer structure on a Ge substrate with an ultrathin AlOx layer. Due to high quality junction, the photodetector features a broadband response of up to 4.6 μm, along with a high specific detectivity of ~1012 Jones, and operates with remarkable stability in ambient conditions as well. Moreover, the highly integrated device arrays based on PtSe2/AlOx/Ge Schottky junction showcases excellent Mid-IR (MIR) imaging capability at room temperature. These findings highlight the promising prospects of 2D topological semimetals for uncooled IR photodetection and imaging applications.
The development of strain sensors with high stretchability and stability is an inevitable requirement for achieving full-range and long-term use of wearable electronic devices. Herein, a resistive micromesh reinforced strain sensor (MRSS) with high stretchability and stability is prepared, consisting of a laser-scribed graphene (LSG) layer and two styrene-block-poly(ethylene-ran-butylene)-block-poly-styrene micromesh layers embedded in Ecoflex. The micromesh reinforced structure endows the MRSS with combined characteristics of a high stretchability (120%), excellent stability (with a repetition error of 0.8% after 11 000 cycles), and outstanding sensitivity (gauge factor up to 2692 beyond 100%). Impressively, the MRSS can still be used continauously within the working range without damage, even if stretched to 300%. Furthermore, compared with different structure sensors, the mechanism of the MRSS with high stretchability and stability is elucidated. What's more, a multilayer finite element model, based on the layered structure of the LSG and the morphology of the cracks, is proposed to investigate the strain sensing behavior and failure mechanism of the MRSS. Finally, due to the outstanding performance, the MRSS not only performes well in monitoring full-range human motions, but also achieves intelligent recognitions of various respiratory activities and gestures assisted by neural network algorithms (the accuracy up to 94.29% and 100%, respectively). This work provides a new approach for designing high-performance resistive strain sensors and shows great potential in full-range and long-term intelligent health management and human–machine interactions applications.
Transition metal dichalcogenides (TMDs) are a promising candidate for developing advanced sensors, particularly for day and night vision systems in vehicles, drones, and security surveillance. While traditional systems rely on separate sensors for different lighting conditions, TMDs can absorb light across a broad-spectrum range. In this study, a dual vision active pixel image sensor array based on bilayer WS2 phototransistors was implemented. The bilayer WS2 film was synthesized using a combined process of radio-frequency sputtering and chemical vapor deposition. The WS2-based thin-film transistors (TFTs) exhibit high average mobility, excellent Ion/Ioff, and uniform electrical properties. The optoelectronic properties of the TFTs array exhibited consistent behavior and can detect visible to near-infrared light with the highest responsivity of 1821 A W−1 (at a wavelength of 405 nm) owing to the photogating effect. Finally, red, green, blue, and near-infrared image sensing capabilities of active pixel image sensor array utilizing light stencil projection were demonstrated. The proposed image sensor array utilizing WS2 phototransistors has the potential to revolutionize the field of vision sensing, which could lead to a range of new opportunities in various applications, including night vision, pedestrian detection, various surveillance, and security systems.
Finding a real thermoelectric (TE) material that excels in various aspects of TE performance, mechanical properties, TE power generation, and cooling is challenging for its commercialization. Herein, we report a novel multifunctional Ge0.78Cd0.06Pb0.1Sb0.06Te material with excellent TE performance and mechanical strength, which is utilized to construct candidate TE power generation and cooling devices near room temperature. Specifically, the effectiveness of band convergence, combined with optimized carrier concentration and electronic quality factor, distinctly boosts the Seebeck coefficient, thus greatly improving the power factor. Advanced electron microscopy observation indicates that complex multi-scale hierarchical structures and strain field distributions lead to ultra-low lattice thermal conductivity, and also effectively enhance mechanical properties. High ZT ~ 0.6 at 303 K, average ZTave ~ 1.18 from 303 to 553 K, and Vickers hardness of ~200 Hv in Ge0.78Cd0.06Pb0.1Sb0.06Te are obtained synchronously. Particularly, a 7-pair TE cooling device with a maximum ΔT of ~45.9 K at Th = 328 K, and a conversion efficiency of ~5.2% at Th = 553 K is achieved in a single-leg device. The present findings demonstrate a unique approach to developing superior multifunctional GeTe-based alloys, opening up a promising avenue for commercial applications.
Accurately forecasting the nonlinear degradation of lithium-ion batteries (LIBs) using early-cycle data can obviously shorten the battery test time, which accelerates battery optimization and production. In this work, a self-adaptive long short-term memory (SA-LSTM) method has been proposed to predict the battery degradation trajectory and battery lifespan with only early cycling data. Specifically, two features were extracted from discharge voltage curves by a time-series-based approach and forecasted to further cycles using SA-LSTM model. The as-obtained features were correlated with the capacity to predict the capacity degradation trajectory by generalized multiple linear regression model. The proposed method achieved an average online prediction error of 6.00% and 6.74% for discharge capacity and end of life, respectively, when using the early-cycle discharge information until 90% capacity retention. Furthermore, the importance of temperature control was highlighted by correlating the features with the average temperature in each cycle. This work develops a self-adaptive data-driven method to accurately predict the cycling life of LIBs, and unveils the underlying degradation mechanism and the importance of controlling environmental temperature.
Over the last decade, perovskite solar cells (PSCs) have drawn extensive attention owing to their high power conversion efficiency (single junction: 26.1%, perovskite/silicon tandem: 33.9%) and low fabrication cost. However, the short lifespan of PSCs with initial efficiency still blocks their practical applications. This operational instability may originate from the intrinsic and extrinsic degradation of materials or devices. Although the lifetime of PSCs has been prolonged through component, crystal, defect, interface, encapsulation engineering, and so on, the systematic analysis of failure regularity for PSCs from the perspective of materials and devices against multiple operating stressors is indispensable. In this review, we start with elaboration of the predominant degradation pathways and mechanism for PSCs under working stressors. Then the strategies for improving long-term durability with respect to fundamental materials, interface designs, and device encapsulation have been summarized. Meanwhile, the key results have been discussed to understand the limitation of assessing PSCs stability, and the potential applications in indoor photovoltaics and wearable electronics are demonstrated. Finally, promising proposals, encompassing material processing, film formation, interface strengthening, structure designing, and device encapsulation, are provided to improve the operational stability of PSCs and promote their commercialization.
A wearable sensing system that can reconstruct dynamic 3D human body models for virtual cloth fitting is highly important in the era of information and metaverse. However, few research has been conducted regarding conformal sensors for accurately measuring the human body circumferences for dynamic 3D human body reshaping. Here, we develop a stretchable spring-sheathed yarn sensor (SSYS) as a smart ruler, for precisely measuring the circumference of human bodies and long-term tracking the movement for the dynamic 3D body reconstruction. The SSYS has a robust property, high resilience, high stability (>18 000), and ultrafast response (12 ms) to external deformation. It is also washable, wearable, tailorable, and durable for long-time wearing. Moreover, geometric, and mechanical behaviors of the SSYS are systematically investigated both theoretically and experimentally. In addition, a transfer learning algorithm that bridges the discrepancy of real and virtual sensing performance is developed, enabling a small body circumference measurement error of 1.79%, noticeably lower than that of traditional learning algorithm. Furtherly, 3D human bodies that are numerically consistent with the actual bodies are reconstructed. The 3D dynamic human body reconstruction based on the wearing sensing system and transfer learning algorithm enables excellent virtual fitting and shirt customization in a smart and highly efficient manner. This wearable sensing technology shows great potential in human-computer interaction, intelligent fitting, specialized protection, sports activities, and human physiological health tracking.
Optoelectronic logic gates have emerged as one of the key candidates for the creation of next generation logic devices. However, current optoelectronic logic gates can provide only one or two logic gates, severely limiting their applications. Here we report a self-powered and mechanically flexible device based on a BaTiO3 ferroelectric film to produce multi-modal logic gates. By exploiting the photo-induced photovoltaic and pyroelectric effects of a Schottky junction which is created between BaTiO3 and LaNiO3, the device is able to provide five different optoelectronic logic gates, which can be operated using input lasers of different wavelength (405 or 785 nm). The mode of operation of the logic gate can be switched by controlling the wavelength and intensity of the input laser, where the switching process is both lossless and reversible. A logic gate array was designed to conduct the five logic operations, with 100% accuracy, thereby providing application potential for the Internet of Things, big data, and secure solutions for data processing and transmission.
In the process of photocatalytic synthesis of ammonia, the kinetics of carrier separation and transport, adsorption of nitrogen, and activation of the N≡N triple bond are key factors that directly affect the efficiency of converting nitrogen to ammonia. Here, we report a new strategy for anchoring MXene quantum dots (MXene QDs) onto the surface of ZnIn2S4 by forming Ti—S bonds, which provide a channel for the rapid separation and transport of charge carriers and effectively extend the lifespan of photogenerated carriers. The unique charge distribution caused by the sulfurization of the MXene QDs further enhances the performance of the photocatalysts for the adsorption and activation of nitrogen. The photocatalytic ammonia synthesis efficiency of MXene QDs–ZnIn2S4 can reach up to 360.5 μmol g−1 h−1. Density functional theory calculations, various in situ techniques, and ultrafast spectroscopy are used to characterize the successful construction of Ti—S bonds and the dynamic nature of excited state charge carriers in MXene QDs–ZnIn2S4, as well as their impact on nitrogen adsorption activation and photocatalytic ammonia synthesis efficiency. This study provides a new example of how to improve nitrogen adsorption and activation in photocatalytic material systems and enhance charge carrier dynamics to achieve efficient photocatalytic nitrogen conversion.