Journal of Materials Chemistry C最新文献

As a crucial parameter in the determination of thermal conductivity, the heat capacity of Cu_2+xZn_1−xSnS₄ (CZTS) has been investigated and analyzed in detail from 2 to 773 K. The effects of the Cu–Zn stoichiometric ratio and phase transition have been quantified and correlated with entropy variation. We confirm that the compounds follow the Dulong–Petit approximation above the Debye temperature θ_D and solve literature discrepancies on CZTS. The in-depth low-temperature heat capacity analysis revealed an approximate image of the energy dependence of the phonon density of state in kesterite, which agrees with the results of first-principles calculations.

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In this study, we reveal a novel NbO_x memristor structure that significantly advances neuromorphic computing by modulating compliance current (CC). This structure emulates the dynamic functionalities of artificial synapses and neurons, addressing the challenge of accurately imitating biological counterparts. Our memristors uniquely exhibit both memory switching (MS) and threshold switching (TS) properties through oxygen content modulation, enabling a single device to undertake diverse synaptic plasticity and neuronal functions. Our findings demonstrate the dual functionality of NbO_x-based memristors: acting as TS and neuron-like devices at high CCs, and as MS and synapse-like elements at low CCs. At a higher CC, the device exhibits effective TS behaviors, including favorable threshold and holding voltages, along with efficient wait and recovery times. This has enabled the creation of a restricted Boltzmann machine (RBM) model for reproducing Modified National Institute of Standards and Technology (MNIST) database images and the implementation of the leaky integrate-and-fire (LIF) model, which in turn opens possibilities for utilizing spike neural network (SNN) frameworks. At lower CCs, the memristor displays synaptic characteristics such as short-term and long-term memory, facilitated by retention loss for offline MNIST simulation. The NbO_x memristor represents a critical component for the future of neuromorphic devices and capable of performing both neuronal and synaptic functions. It paves the way for sophisticated, integrated computational models, thereby significantly contributing to the neuromorphic engineering field. Through comprehensive structural and functional analyses, this study underscores the potential of NbO_x memristors in neuromorphic computing and lays the foundation for future high-performance neuromorphic device advancements.

Gallium nitride (GaN) based high elect mobility transistors (HEMTs) possess a multitude of excellent characteristics, enabling them to overcome the performance limitations of traditional silicon-based power devices. This comprehensive review discusses the challenges in the fabrication processes and device structures of p-type GaN (p-GaN) gate HEMTs on silicon substrates. Mainly by using Citespace software, this paper demonstrates the analytical results of keyword co-occurrence based on references related to p-GaN gate HEMTs from the core collection of Web of Science, revealing the prominent research topics in this area and discussing the relevant influencing factors and mechanisms of the electrical performance of p-GaN gate HEMTs. Moreover, various methods for optimizing the fabrication processes and device structures proposed in recent years are also reviewed. The future development of p-GaN gate HEMTs is explored, including the integration with more devices, the development of appropriate reliability verification standards, the expansion of production capabilities, and the incorporation of emerging two-dimensional materials.

Conducting polymers can be dynamically switched between being optically metallic (negative real permittivity) and dielectric (positive real permittivity) by varying their redox state. This has enabled nanoantennas with plasmonic resonances that can be reversibly turned on/off, opening for applications in dynamic metaoptics, reflective displays, and smart windows. However, previous reports on conducting polymer plasmonics were limited to p-type polymers. Here, we show that a highly conducting n-type polymer, called poly(benzodifurandione) (PBFDO), can also provide optically metallic properties and be used to make dynamic optical nanoantennas. The doped version of the polymer becomes metallic at wavelengths above around 700 nm, leading to plasmonic extinction peaks for nanodisks made from the material. These peaks can be reversibly switched off and on electrically or chemically by varying the doping level of the polymer. The study extends the field of dynamic polymer plasmonics to n-type materials and broadens the application areas of PBFDO.

Recently, MXene-like MOenes have emerged as promising candidates for next-generation two-dimensional optoelectronic devices due to their exceptional electrical and optical properties. By using first-principles calculations, we design a novel two-dimensional 2H-M₂O₃ (M = Ti, Zr) through the oxygen functionalization of the M₂O monolayer, which shows high mechanical, dynamic, and thermal stabilities. The calculation results reveal a relatively small band gap of 0.49 and 0.94 eV and exciton binding energy of 0.26 and 0.46 eV for 2H-Ti₂O₃ and 2H-Zr₂O₃ monolayers, respectively. Importantly, they exhibit good light absorption in the infrared range with a first excitonic peak at 0.31 and 0.54 eV, respectively. Notably, a wide transparent window from the visible to ultraviolet region in linear optical spectra is found due to the large gap within the valence bands. The octahedral distortion and small optical gap of the 2H-M₂O₃ monolayer result in a large second harmonic generation (SHG) coefficient of approximately 4000 pm V⁻¹. This work optimizes the electrical and optical properties of MOenes using O termination, providing high linear and SHG response at specific wavelengths.

Our 2024 Emerging Investigators themed collections gather some of the best research being conducted by scientists in the early stages of their independent career. Each contributor was recommended as carrying out work with the potential to influence future directions in materials chemistry. Congratulations to all of the researchers featured, we hope you enjoy reading this collection.

The development of infrared photodetectors is increasingly moving towards the realization of large-scale, cost-effective integrated systems. Currently, silicon (Si), indium gallium arsenide (InGaAs), and mercury cadmium telluride (HgCdTe) dominate infrared photodetectors, but due to the ever-increasing performance requirements and the complexity of emerging application scenarios, a new generation of detector technologies is imperative. Colloidal quantum dots (CQDs), which are compatible with existing silicon-based microelectronics, with low manufacturing costs and simplified processing, are ideal alternatives. Hg- or Pb-based infrared photodetectors have been widely studied owing to their excellent performance. Nevertheless, the presence of heavy metal elements greatly limits the application scenarios of the detectors. Therefore, heavy metal-free (HMF) CQD-based infrared photodetectors solve the above problem from the source. In this work, the latest advancements in the synthesis of HMF CQDs and a brief overview of the development of HMF CQD-based infrared photodetectors are given. Within the context of this field, we summarize the possible forward-looking directions and obstacles.

Correction for ‘Enhanced charge transport from Pd-doping in CsPbBr₃ quantum dots for efficient photoelectrocatalytic water splitting’ by Wenxiao Gong et al., J. Mater. Chem. C, 2023, 11, 6963–6970, https://doi.org/10.1039/D3TC00115F.

Pure phase KYb(MoO₄)₂:Er³⁺ phosphors doped with different concentrations of Zn²⁺ ions were prepared by a high temperature solid phase method. Based on XRD refinement results, some Yb³⁺ ions and K⁺ ions were replaced by Zn²⁺ ions. The upconversion luminescence (UCL) spectra of 980 nm laser excitation show that KYb(MoO₄)₂:Er³⁺ emits single near-infrared light and KYb(MoO₄)₂:Er³⁺,Zn²⁺ presents multi-modal UCL emission. The optimal doping concentration of Zn²⁺ ions was 0.08. Meanwhile, the energy transfer process of UCL was revealed by optical characterization methods. The temperature sensing characteristics of the phosphor were tested in the temperature range of 298–523 K. The phosphor exhibits thermal enhancement. Variable temperature XRD from 298 K to 523 K resulted in a slight enlargement and expansion in the refinement of cell parameters and volume. This indicates that thermal enhancement is attributed to the lattice structure distortion caused by doping of Zn²⁺ ions, not caused by phase transformation and negative thermal expansion. In addition, the relative and absolute sensitivities of the phosphor were 1.1% K⁻¹ at 298 K and 1.73% K⁻¹ at 348 K, respectively. This provides a new approach and opens up new avenues for the theory of thermally enhanced luminescence.