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Diamond is a highly suitable material for X-ray detectors that can function effectively in harsh environments due to its unique properties such as ultrawide bandgap, high radiation resistance, excellent carrier mobility as well as remarkable chemical and thermal stability. However, the sensitivity of diamond X-ray detectors needs further improvement due to the relatively low X-ray absorption efficiency of diamond, and the exploration of single-crystal diamond array imaging still remains unexplored. In the current work, a 10 × 10 X-ray photodetector array was constructed from single-crystal diamond. To improve the sensitivity of the diamond X-ray detector, an asymmetric sandwich electrode structure was utilized. Additionally, trenches were created through laser cutting to prevent crosstalk between adjacent pixels. The diamond X-ray detector array exhibits exceptional performance, including a low detection limit of 4.9 nGy s−1, a sensitivity of 14.3 mC Gy−1 cm−2, and a light-dark current ratio of 18,312, which are among the most favorable values ever reported for diamond X-ray detectors. Furthermore, these diamond X-ray detectors can operate at high temperatures up to 450 °C, making them suitable for development in harsh environments.

A miniaturized photoacoustic spectroscopy-based gas sensor is proposed for the purpose of detecting sub-ppm-level carbonyl sulfide (OCS) using a tunable mid-infrared interband cascade laser (ICL) and a Helmholtz photoacoustic cell. The tuning characteristics of the tunable ICL with a center wavelength of 4823.3 nm were investigated to achieve the optimal driving parameters. A Helmholtz photoacoustic cell with a volume of ∼2.45 mL was designed and optimized to miniaturize the measurement system. By optimizing the modulation parameters and signal processing, the system was verified to have a good linear response to OCS concentration. With a lock-in amplifier integration time of 10 s, the 1σ noise standard deviation in differential mode was 0.84 mV and a minimum detection limit (MDL) of 409.2 ppbV was achieved at atmospheric pressure and room temperature.

Abstract Diamond possesses excellent thermal conductivity and tunable bandgap. Currently, the high‐pressure, high‐temperature, and chemical vapor deposition methods are the most promising strategies for the commercial‐scale production of synthetic diamond. Although diamond has been extensively employed in jewelry and cutting/grinding tasks, the realization of its high‐end applications through microstructure engineering has long been sought. Herein, we discuss the microstructures encountered in diamond and further concentrate on cutting‐edge investigations utilizing electron microscopy techniques to illuminate the transition mechanism between graphite and diamond during the synthesis and device constructions. The impacts of distinct microstructures on the electrical applications of diamond, especially the photoelectrical, electrical, and thermal properties, are elaborated. The recently reported elastic and plastic deformations revealed through in situ microscopy techniques are also summarized. Finally, the limitations, perspectives, and corresponding solutions are proposed.

Abstract Along with the increasing integration density and decreased feature size of current semiconductor technology, heterointegration of the Si‐based devices with diamond has acted as a promising strategy to relieve the existing heat dissipation problem. As one of the heterointegration methods, the microwave plasma chemical vapor deposition (MPCVD) method is utilized to synthesize large‐scale diamond films on a Si substrate, while distinct structures appear at the Si‐diamond interface. Investigation of the formation mechanisms and modulation strategies of the interface is crucial to optimize the heat dissipation behaviors. By taking advantage of electron microscopy, the formation of the epitaxial β‐SiC interlayer is found to be caused by the interaction between the anisotropically sputtered Si and the deposited amorphous carbon. Compared with the randomly oriented β‐SiC interlayer, larger diamond grain sizes can be obtained on the epitaxial β‐SiC interlayer under the same synthesis condition. Moreover, due to the competitive interfacial reactions, the epitaxial β‐SiC interlayer thickness can be reduced by increasing the CH4/H2 ratio (from 3% to 10%), while further increase in the ratio (to 20%) can lead to the broken of the epitaxial relationship. The above findings are expected to provide interfacial design strategies for multiple large‐scale diamond applications.

Abstract Diamond, with ultrahigh hardness, high wear resistance, high thermal conductivity, and so forth, has attracted worldwide attention. However, researchers found emergent reactions at the interfaces between diamond and ferrous materials, which significantly affects the performance of diamond‐based devices. Herein, combing experiments and theoretical calculations, taking diamond–iron (Fe) interface as a prototype, the counter‐diffusion mechanism of Fe/carbon atoms has been established. Surprisingly, it is identified that Fe and diamond first form a coherent interface, and then Fe atoms diffuse into diamond and prefer the carbon vacancies sites. Meanwhile, the relaxed carbon atoms diffuse into the Fe lattice, forming Fe3C. Moreover, graphite is observed at the Fe3C surface when Fe3C is over‐saturated by carbon atoms. The present findings are expected to offer new insights into the atomic mechanism for diamond‐ferrous material's interfacial reactions, benefiting diamond‐based device applications.

Here the author study Self-trapped exciton emission for multiphoton excited luminescence in ZnO nanoparticle which until now have not been explored. They provide a reason for the emission enhancement and apply these materials in optical imaging for a proof of concept.

The rapid development of information and communication technology has driven the demand for higher data transmission rates. Multi-core optical fiber, with its ability to transmit multiple signals simultaneously, has emerged as a promising solution to meet this demand. Additionally, due to its characteristics such as multi-channel transmission, high integration, spatial flexibility, and versatility, multi-core optical fibers hold vast potential in sensing applications. However, the manufacturing technology of multi-core fiber is still in its early stages, facing challenges such as the design and fabrication of high-quality cores, efficient coupling between cores, and the reduction of crosstalk. In this paper, an overview of the current status and future prospects of multi-core fiber manufacturing technology has been presented, and their limitations will be discussed. Some potential solutions to overcome these challenges will be proposed. Their potential applications in optical fiber sensing will also be summarized.

Abstract Recent experimental and theoretical studies demonstrated microwave mode cooling and cavity quantum electrodynamics (C-QED) effects at room temperature by using optically cooled nitrogen-vacancy (NV) spins. In this article, we consider improvements of these effects by exploring parameters in recent diamond maser experiments with a high frequency microwave resonator. By accounting for the rich electronic and spin levels, we provide a more complete treatment of optical pumping and dissipation in NV centers, and study the dependence of system performance on laser power. We predict the reduction of microwave photon number down to 261 (equivalent to a temperature of 116 K), about five times lower than the values reported recently. We also predict the laser-power controlled C-QED effects across weak-to-strong coupling regimes, and observe saturation of these effects under strong laser pumping. Our model can be modified straightforwardly to investigate similar effects with other solid-state spins and possible C-QED effects in maser operation.

Abstract Carbon nanogels (CNGs) with dual ability of reactive oxygen species (ROS) imaging and photodynamic therapy have been designed with self‐assembled chemiluminescent carbonized polymer dots (CPDs). With efficient deep‐red/near‐infrared chemiluminescence (CL) emission and distinctive photodynamic capacity, the H2O2‐driven chemiluminescent CNGs are further designed by assembling the polymeric conjugate and CL donors, enabling an in vitro and in vivo ROS bioimaging capability in animal inflammation models and a high‐performance therapy for xenograft tumors. Mechanistically, ROS generated in inflammatory sites or tumor microenvironment can trigger the chemically initiated electron exchange luminescence in the chemical reaction of peroxalate and H2O2, enabling in vivo CL imaging. Meanwhile, part of the excited‐state electrons will transfer to the ambient H2O or dissolved oxygen and in turn lead to the type I and type II photochemical ROS production of hydroxyl radicals or singlet oxygen, endowing the apoptosis of tumor cells and thus enabling cancer therapy. These results open up a new avenue for the design of multifunctional nanomaterials for bioimaging and antienoplastic agents.

Abstract Application of long‐persistent luminescence (LPL) materials in many technological fields is in the spotlight. However, the exploration of undoped persistent luminescent materials with high emission efficiency, robust stability, and long persistent duration remains challenging. Here, inorganic cesium cadmium chlorine (CsCdCl3) is developed, featuring remarkable LPL characteristics at room temperature, which is synthesized by a facile hydrothermal method. Excited by ultraviolet light, the CsCdCl3 crystals exhibit an intense yellow emission with a large photoluminescence quantum yield of ≈90%. Different from the reported systems with lanthanides or transition metals doping, the CsCdCl3 crystals without dopants perform yellow LPL with a long duration of 6000 s. Joint experiment‐theory characterizations reveal the intrinsic point defects of CsCdCl3 act as the trap centers of excited electrons and the carrier de‐trapping process from such trap sites to localized emission centers contributes to the LPL. Encouraged by the attractive fluorescence and persistent luminescence as well as good stability of CsCdCl3 against environment oxygen/moisture (75%), heat (100 °C for 10 h), and ultraviolet light irradiation, an effective dual‐mode information storage‐reading application is demonstrated. The results open up a new frontier for exploring LPL materials without dopants and provide an opportunity for advanced information storage compatible for practical applications.

Abstract Phosphor‐converting white light‐emitting diodes (WLEDs) are promising and particularly appealing solid‐state light sources, which are expected to change the way we light our homes and businesses. Lead‐halide perovskites have recently received extensive research attention as a new class of phosphors in WLEDs owing to their high photoluminescence quantum yield, tunable fluorescence emission, and the facile processing technique. However, the stability issues and the lead toxicity of such perovskites severely restrict their commercialization and practical applications. In this review, we first present a discussion on the recently developed luminescent lead‐free halide perovskites and perovskite derivatives by discussing their various design routes and emission mechanisms. Second, we introduce and compare three types of phosphor‐converting WLEDs with different cell configurations, and then discuss the recent advances and limitations in WLEDs based on lead‐free metal‐halide materials. Finally, we highlight current existing challenges and future development directions for developing high‐performance WLEDs.

A CO sensor based on photoacoustic spectroscopy (PAS) with empirical mode decomposition (EMD) algorithm is investigated and demonstrated in this paper. In the PAS system, the complicated photo-thermal-acoustic conversion is a nonlinear and non-stationary process and contains various noise. In order to compensate the low signal-to-noise ratio (SNR), the EMD is introduced in the PAS system to deal with the photoacoustic signal. The experimental results show that a gain factor of ∼3.0 on the SNR is achieved and the sensor has an excellent linear response to the gas concentration. The minimum detection level (MDL) for CO detection is reduced to 1.14 ppm with a 300 ms integrated time at room temperature and atmospheric pressure.

Abstract Nanomaterials based pressure sensors have obtained world‐wide research interest due to their promising potential applications in health monitoring, artificial intelligence, and electronic skin (e‐skin). Despite the recent progress in sensitivity and detection range of the pressure sensors, the relatively high thickness of the active films has obstructed their applications for e‐skin and degraded the comfortability as wearable devices. We hereby report for the first time a novel pressure sensor based on two‐dimensional metal oxide nanosheets where the gaps between neighboring nanosheets are adjustable. The pressure sensors show a sensitivity of up to 7.2 × 106 kPa–1, which is the highest value ever reported for a pressure sensor. Additionally, the sensor shows good repeatability and excellent stability. The pressure‐sensing ranges can be tuned by adjusting the coverage of the nanosheet film. This work presents an effective strategy to develop ultrathin pressure sensors.

X-ray detectors have numerous applications in medical imaging, industrial inspection, and crystal structure analysis. Gallium oxide (Ga2O3) shows potential as a material for high-performance X-ray detectors due to its wide bandgap, relatively high mass attenuation coefficient, and resistance to radiation damage. In this study, we present Sn-doped Ga2O3 microwire detectors for solar-blind and X-ray detection. The developed detectors exhibit a switching ratio of 1.66 × 102 under X-ray irradiation and can operate stably from room temperature to 623 K, which is one of the highest reported operating temperatures for Ga2O3 X-ray detectors to date. These findings offer a promising new direction for the design of Ga2O3-based X-ray detectors.

A challenge for slowly relaxing carbon monoxide (CO) molecules detection using photoacoustic spectroscopy (PAS) is to promote the vibration-translation (V-T) relaxation process. Addressing this challenge, a sensitivity enhanced photoacoustic CO sensor with sulfur hexafluoride (SF6) as the promotor is investigated and demonstrated. A 1568 nm near-infrared (NIR) laser diode and a customized optical amplifier are used as the excitation source to generate the photoacoustic signal. A differential photoacoustic cell is simulated and designed to obtain identical laminar flow distribution in the resonant cell to suppress the flow noise. The modulation frequency and added SF6 volume ratio are optimized experimentally to achieve optimal sensitivity. Feasibility and performance of the CO sensor with a small amount of SF6 as promotor is discussed and evaluated, obtaining a ~ 2 times improvement of signal value compared to the one with pure N2 background and resulting in a minimum detection limit of 467.5 ppb for CO detection.

Abstract Research on lead‐halide perovskites for photovoltaic and optoelectronic applications represents a rapidly developing field of optoelectronics on account of their remarkable optoelectronic properties, including large absorption coefficient, low‐temperature solution processability, tunable bandgap, high‐carrier mobility, and so on. Unfortunately, the toxicity of metal Pb and intrinsic instability of lead‐halide perovskites are still big obstacles for their practical applications and future commercial development. Therefore, various lead‐free eco‐friendly perovskites and their derivatives have been alternatively explored to overcome the above hurdles. In this review, the preparation methods, structures, optical characteristics, and stability of lead‐free metal halide perovskites are summarized according to different dimensions at molecular level. Furthermore, we emphatically introduce the optoelectronic properties of low‐dimensional lead‐free halides with broadband emission originated from the self‐trapped excitons. Then, we give a brief description of preliminary exploration results and significant achievements of optically excited white light‐emitting devices (WLEDs) and electrically excited multi‐color LEDs. Finally, this review was finished with a critical perspective into the potential challenging issues of this rapidly evolving fields.

Abstract Machine vision systems (MVSs) are an important component of intelligent systems, such as autonomous vehicles and robots. However, with the continuous increase in data and new application scenarios, new requirements are put forward for the next generation of MVS. There is an urgent need to find new material systems to complement the existing semiconductor technology based on thin‐film materials, and new architectures must be explored to improve efficiency. Because of their unique physical properties, two‐dimensional (2D) materials have received extensive attention for use in MVSs, especially in biomimetic ones: the human visual system, which can process complex visual information with low power consumption, provides a model for next‐generation MVSs. This review paper summarizes the progress and challenges of applying 2D material photodetectors in sense‐memory‐computational integration and biomimetic image sensors for machine vision.

Chemical vapor deposition (CVD) diamond crystal is considered as an ideal material platform for Raman lasers with both high power and good beam quality due to its excellent Raman and thermal characteristics. With the continuous development of CVD diamond crystal growth technology, diamond Raman lasers (DRLs) have shown significant advantages in achieving wavelength expansion with both high beam quality and high-power operation. However, with the output power of DRLs reaching the kilowatt level, the adverse effect of the thermal impact on the beam quality is progressively worsening. Aiming to enunciate the underlying restrictions of the thermal effects for high-power DRLs (e.g., recently reported 1.2 kW), we here establish a thermal-structural coupling model, based on which the influence of the pump power, cavity structure, and crystal size have been systematically studied. The results show that a symmetrical concentric cavity has less thermal impact on the device than an asymmetrical concentric cavity. Under the ideal heat dissipation condition, the highest temperature rise in the diamond crystal is 23.4 K for an output power of ~2.8 kW. The transient simulation further shows that the heating and cooling process of DRLs is almost unaffected by the pump power, and the times to reach a steady state are only 1.5 ms and 2.5 ms, respectively. In addition, it is also found that increasing the curvature radius of the cavity mirror, the length and width of the crystal, or decreasing the thickness of the crystal is beneficial to alleviating the thermal impact of the device. The findings of this work provide some helpful insights into the design of the cavity structure and heat dissipation system of DRLs, which might facilitate their future development towards a higher power.

Abstract Photodetectors built from conventional bulk materials such as silicon, III–V or II–VI compound semiconductors are one of the most ubiquitous types of technology in use today. The past decade has witnessed a dramatic increase in interest in emerging photodetectors based on perovskite materials driven by the growing demands for uncooled, low‐cost, lightweight, and even flexible photodetection technology. Though perovskite has good electrical and optical properties, perovskite‐based photodetectors always suffer from nonideal quantum efficiency and high‐power consumption. Joint manipulation of electrons and photons in perovskite photodetectors is a promising strategy to improve detection efficiency. In this review, electrical and optical characteristics of typical types of perovskite photodetectors are first summarized. Electrical manipulations of electrons in perovskite photodetectors are discussed. Then, artificial photonic nanostructures for photon manipulations are detailed to improve light absorption efficiency. By reviewing the manipulation of electrons and photons in perovskite photodetectors, this review aims to provide strategies to achieve high‐performance photodetectors.

Photovoltaic devices based on 2D materials still suffer from low quantum efficiencies due to interfacial charge recombination and inefficient contacts. Here, the authors design photovoltaic detectors and photodiodes based on MoS2 and doped AsP heterojunction with unilateral depletion region reporting high external quantum efficiency of 71% under zero applied bias.

Metal halide perovskite nanocrystals (NCs), as a new class of light-emitting and light-harvesting materials, have recently attracted intensive attention for an impressive variety of optoelectronic applications. However, the lead toxicity and poor stability of such materials severely restrict their practical applications and future commercialization. Lead-free perovskite NCs and their derivatives, designed by the reasonable chemical substitution of Pb with other nontoxic elements, are recently booming as an attractive alternative to lead-based counterparts. In this review, we firstly present a comprehensive overview of currently explored lead-free perovskite NCs with an emphasis on their design routes, morphologies, optoelectronic properties, and environmental stability issues. Then, we discuss the preliminary achievements of lead-free perovskite NCs in versatile optoelectronic applications, such as light-emitting devices, solar cells, photodetectors, and photocatalysis. We finish this review with a critical outlook into the currently existing challenges and possible development opportunities of this rapidly evolving field.

III–V group nanomaterials with a narrow bandgap have been demonstrated to be promising building blocks in future electronic and optoelectronic devices. Thus, revealing the underlying structural evolutions under various external stimuli is quite necessary. To present a clear view about the structure–property relationship of III–V nanowires (NWs), this review mainly focuses on key procedures involved in the synthesis, fabrication, and application of III–V materials-based devices. We summarized the influence of synthesis methods on the nanostructures (NWs, nanodots and nanosheets) and presented the role of catalyst/droplet on their synthesis process through in situ techniques. To provide valuable guidance for device design, we further summarize the influence of structural parameters (phase, defects and orientation) on their electrical, optical, mechanical and electromechanical properties. Moreover, the dissolution and contact formation processes under heat, electric field and ionic water environments are further demonstrated at the atomic level for the evaluation of structural stability of III–V NWs. Finally, the promising applications of III–V materials in the energy-storage field are introduced.

Abstract Assembling nanomaterials into hybrid structures provides a promising and flexible route to reach ultrahigh responsivity by introducing a trap‐assisted gain (G) mechanism. However, the high‐gain photodetectors benefitting from long carrier lifetime often possess slow response time (t) due to the inherent G–t tradeoff. Here, a light‐driven junction field‐effect transistor (LJFET), consisting of an n‐type ZnO belt as the channel material and a p‐type WSe2 nanosheet as a photoactive gate material, to break the G–t tradeoff through decoupling the gain from carrier lifetime is reported. The photoactive gate material WSe2 under illumination enables a conductive path for externally applied voltage, which modulates the depletion region within the ZnO channel efficiently. The gain and response time are separately determined by the field effect modulation and the switching speed of LJFET. As a result, a high responsivity of 4.83 × 103 A W−1 with a gain of ≈104 and a rapid response time of ≈10 µs are obtained simultaneously. The LJFET architecture offers a new approach to realize high‐gain and fast‐response photodetectors without the G–t tradeoff.

Achieving high-performance materials with superior mechanical properties and electrical conductivity, especially in large-sized bulk forms, has always been the goal. However, it remains a grand challenge due to the inherent trade-off between these properties. Herein, by employing nanodiamonds as precursors, centimeter-sized diamond/graphene composites were synthesized under moderate pressure and temperature conditions (12 GPa and 1,300 to 1,500 °C), and the composites consisted of ultrafine diamond grains and few-layer graphene domains interconnected through covalently bonded interfaces. The composites exhibit a remarkable electrical conductivity of 2.0 x 104 S m-1 at room temperature, a Vickers hardness of up to ~55.8 GPa, and a toughness of 10.8 to 19.8 MPa m1/2. Theoretical calculations indicate that the transformation energy barrier for the graphitization of diamond surface is lower than that for diamond growth directly from conventional sp² carbon materials, allowing the synthesis of such diamond composites under mild conditions. The above results pave the way for realizing large-sized diamond-based materials with ultrahigh electrical conductivity and superior mechanical properties simultaneously under moderate synthesis conditions, which will facilitate their large-scale applications in a variety of fields. [ABSTRACT FROM AUTHOR]