宽禁带半导体材料特性及生长技术

叙述了宽带半导体材料ＳｉＣ、ＧａＮ的主要特性和生长方法,并对其发展动态和存在问题进行了简要评述。     

“宽禁带电力电子器件的原理与应用”课程建设

为了满足我校电气工程及其自动化专业本科教育培养适应电力电子行业需求人才,结合目前功率半导体器件和电力电子技术发展趋势,建设紧扣第三代半导体器件的《宽禁带电力电子器件的原理与应用》课程。教学内容有机分为三大模块和七个学习阶段,逐步推进。在教学过程中,引入“教师引导、自主学习、问题导向、扩展视野”的教学理念,将启发式、讨论式、任务驱动式等多种教学方法互相配合使用,充分激发学生的学习兴趣,加深对器件知识的理解,强化器件测试和应用能力,着力培养学生分析问题和解决问题的能力。     

Machine Vision Based on an Ultra-Wide Bandgap 2D Semiconductor AsSbO3

Facing the future development trend of miniaturization and intelligence of electronic devices, solar-blind photodetectors based on ultrawide-bandgap 2D semiconductors have the advantages of low dark current, and high signal-to-noise ratio, as well as the features of micro-nanometer miniaturization and multi-functionalization of 2D material devices, which have potential applications in the photoelectric sensor part of high-performance machine vision systems. This study reports a 2D oxide semiconductor, AsSbO₃, with an ultrawide bandgap (4.997 eV for monolayer and 4.4 eV for multilayer) to be used to fabricate highly selective solar-blind UV photodetectors, of which the dark current as low as 100 fA and rejection ratio of UV-C and UV-A reaches 7.6 × 10³. Under 239 nm incident light, the responsivity is 105 mA W⁻¹ and the detectivity is 7.58 × 10¹² Jones. Owing to the remarkable anisotropic crystal structure, AsSbO₃ also shows significant linear dichroism and nonlinear optical properties. Finally, a simple machine vision system is simulated by combining the real-time imaging function in solar-blind UV with a convolutional neural network. This study enriches the material system of ultrawide-bandgap 2D semiconductors and provides insight into the future development of high-performance solar-blind UV optoelectronic devices.     

Interface Engineering Enhances the Photovoltaic Performance of Wide Bandgap FAPbBr3 Perovskite for Application in Low-Light Environments

Underwater solar cells (UWSCs) provide an ideal alternative to the energy supply for long-endurance autonomous underwater vehicles. However, different from conventional solar cells situated on land or above water, UWSCs give preference to use wide bandgap semiconductors (≥1.8 eV) as light absorber to match underwater solar spectra. Among wide bandgap semiconductors, FAPbBr₃ perovskite is under prime consideration owing to its matching optical bandgap (≈2.3 eV), outstanding photoelectric properties, easier processability, etc. Unfortunately, for FAPbBr₃ solar cells, substantial interface defects greatly limit the charge carrier extraction efficiency, thus limiting the device performance, especially in underwater low-light environments. This study employs a molecular self-assembly strategy to effectively eliminate the interfacial defects. As a result, a great improvement in power conversion efficiency (PCE) from 6.44% to 7.49% is obtained, which is among the best efficiency reported for inverted FAPbBr₃ solar cells up to date. Besides, a champion PCE of 30% is obtained under 520 nm monochromatic light irradiation (4.8 mW cm⁻²). These results demonstrate that FAPbBr₃ solar cells present a tremendously promising application in UWSCs.     

Full 3D Printing of Stretchable Piezoresistive Sensor with Hierarchical Porosity and Multimodulus Architecture

A soft piezoresistive sensor with its unique characteristics, such as human skin, light weight, and multiple functions, yields a variety of possible practical applications to skin‐attachable electronics, human–machine interfaces, and electronic skins. However, conventional filler‐matrix piezoresistive sensors often suffer from unsatisfactory sensitivity or insufficient measurement range, as well as significant cross‐correlation between out‐of‐plane pressure and in‐plane extension. Here, a stretchable piezoresistive sensor (SPS) is realized by combining a hierarchically porous sensing element with a multimodulus device architecture via a full 3D printing process. As a result, the sensor exhibits high sensitivity (5.54 kPa^?1), large measurement range (from 10 Pa to 800 kPa), limited cross‐correlation, and excellent durability. Meanwhile, benefiting from the porous structure and mechanical mismatch design, which efficiently distributes the stress away from the sensing element, the device experiences only 7% resistance change at 50% stretching. This approach is employed to rapidly program and readily manufacture stylish, all‐in‐one, functional devices for various applications, demonstrating that the technique is promising for customized stretchable electronics.     

对有源相控阵雷达的一些新要求与宽禁带半导体器件的应用

讨论对有源相控阵雷达和T／R组件的一些新要求。宽禁带半导体材料与器件的主要性能与特点在文中作了简要介绍。宽禁带半导体器件在有源相控阵雷达中的潜在应用在文中也进行了讨论。     

Highly Stretchable Conductors Integrated with a Conductive Carbon Nanotube/Graphene Network and 3D Porous Poly(dimethylsiloxane)

Here, a novel and facile method is reported for manufacturing a new stretchable conductive material that integrates a hybrid three dimensional (3D) carbon nanotube (CNT)/reduced graphene oxide (rGO) network with a porous poly(dimethylsiloxane) (p‐PDMS) elastomer (pPCG). This reciprocal architecture not only alleviates the aggregation of carbon nanofillers but also significantly improves the conductivity of pPCG under large strains. Consequently, the pPCG exhibits high electrical conductivity with a low nanofiller loading (27 S m^?1 with 2 wt% CNTs/graphene) and a notable retention capability after bending and stretching. The simulation of the mechanical properties of the p‐PDMS model demonstrates that an extremely large applied strain (ε_appl) can be accommodated through local rotations and bending of cell walls. Thus, after a slight decrease, the conductivity of pPCG can continue to remain constant even as the strain increases to 50%. In general, this architecture of pPCG with a combination of a porous polymer substrate and 3D carbon nanofiller network possesses considerable potential for numerous applications in next‐generation stretchable electronics.     

Tailored and Highly Stretchable Sensor Prepared by Crosslinking an Enhanced 3D Printed UV-Curable Sacrificial Mold

Taking advantage of unlimited geometry design, 3D printed sacrificial mold cast with highly conductive polymer composites is used to prepare a sensor with designed structures. However, the disposal of the mold in a mild condition while the refined structures can be maintained is still a challenge. Herein, a bifunctional monomer hydrolyzable hindered urea acrylate is synthesized to create a cross-linked polymer network, preventing the dissolution of printed parts in the uncured resin. 3D printed scaffolds can be hydrolyzed in hot water, which provides an attractive option for sacrificial molds. Also, a porous flexible strain sensor (PFSS) is fabricated by casting polyurethane/carbon nanotubes composites into the sacrificial molds, which demonstrates a high stretchability (≈510%) and an excellent recoverability. Meantime, the pressure sensitivity (0.111 kPa⁻¹) and a long-term electrical resistance of PFSS is characterized. The resistance response signal remains nearly unchanged after 100 compressive loading cycles at a large strain of 60%. Benefiting from the design freedom of 3D printing, a practical application of the PFSS with a complex and customized structure to monitor human motion is demonstrated. These results prove that the sacrificial molding process has great potential for user-specific stretchable wearable devices.     

Stretchable Supercapacitor with Adjustable Volumetric Capacitance Based on 3D Interdigital Electrodes

Reduced graphene oxide (rGO)‐based materials have shown good performance as electrodes in flexible energy storage devices owing to their physical properties, high specific surface area, and excellent electrical conductivity. Here, a novel road is reported for fabricating high‐performance supercapacitors based on 3D rGO electrodes and solid electrolyte multilayers via pressure spray printing and machine coating. These supercapacitors demonstrate high and adjustable volumetric capacitance, excellent flexibility, and stretchability. The results show that this commercial strategy has its essential merits such as low‐cost, inexpensive, and simple fabrication for large area production. These properties are in the favor of fabricating high‐performance supercapacitor to meet the practical energy demands in devices, especially flexible electronic devices. Furthermore, this novel 3D interdigital electrode concept can be widely applied to other energy devices for enhancing performances and to other micro devices for reducing cost.     

Colloid-Mediated Fabrication of a 3D Pollen Sponge for Oil Remediation Applications

There is tremendous interest in developing 3D scaffolds from natural materials for a wide range of healthcare, energy, photonic, and environmental science applications. To date, most natural materials that are used to make 3D scaffolds consist of fibril structures; however, it would be advantageous to explore the development of scaffolds from natural materials with distinct supramolecular structures. Herein, the fabrication of a mechanically responsive pollen sponge that exhibits tunable 3D scaffold properties and is useful for oil remediation applications is reported. By using pollen-based microgel particles as colloidal building blocks, the sponge fabrication process is optimized by tuning the processing conditions during freeze-drying and thermal annealing steps. Stearic acid functionalization transforms the pollen sponge into a hydrophobic scaffold that can readily and repeatedly absorb oil and other organic solvents from contaminated water sources, with similar performance levels to commercial, synthetic polymer-based absorbents and an improved environmental footprint.     

3D Printing of Hydrogels for Stretchable Ionotronic Devices

In the booming development of flexible electronics represented by electronic skins, soft robots, and human–machine interfaces, 3D printing of hydrogels, an approach used by the biofabrication community, is drawing attention from researchers working on hydrogel-based stretchable ionotronic devices. Such devices can greatly benefit from the excellent patterning capability of 3D printing in three dimensions, as well as the free design complexity and easy upscale potential. Compared to the advanced stage of 3D bioprinting, 3D printing of hydrogel ionotronic devices is in its infancy due to the difficulty in balancing printability, ionic conductivity, shape fidelity, stretchability, and other functionalities. In this review, a guideline is provided on how to utilize the power of 3D printing in building high-performance hydrogel-based stretchable ionotronic devices mainly from a materials’ point of view, highlighting the systematic approach to balancing the printability, printing quality, and performance of printed devices. Various 3D printing methods for hydrogels are introduced, and then the ink design principles, balancing printing quality, printed functions, such as elastic conductivity, self-healing ability, and device (e.g., flexible sensors, shape-morphing actuators, soft robots, electroluminescent devices, and electrochemical biosensors) performances are discussed. In conclusion, perspectives on the future directions of this exciting field are presented.     

A Highly Efficient,Blue‐Phosphorescent Device Based on a Wide‐Bandgap Host/FIrpic: Rational Design of the Carbazole and Phosphine Oxide Moieties on Tetraphenylsilane

A new series of wide‐bandgap materials, 4‐dipenylphosphine oxide‐4′‐9H‐carbazol‐9‐yl‐tetraphenylsilane (CSPO), 4‐diphenylphosphine oxide‐4′,4″‐di(9H‐carbazol‐9‐yl)‐tetraphenylsilane (pDCSPO), 4‐diphenylphosphine oxide ‐4′‐[3‐(9H‐carbazol‐9‐yl)‐carbazole‐9‐yl]‐tetraphenylsilane (DCSPO), 4‐diphenylphosphine oxide‐4′,4″,4″′‐tri(9H‐carbazol‐9‐yl)‐tetraphenylsilane (pTCSPO) and 4‐diphenylphosphine oxide ‐4′‐[3,6‐di(9H‐carbazol‐9‐yl)‐9H‐carbazol‐9‐yl]‐tetraphenylsilane (TCSPO), containing different ratios and linking fashions of p‐type carbazole units and n‐type phosphine oxide units, are designed and obtained. DCSPO is the best host in FIrpic‐doped devices for this series of compounds. By utilizing DCzSi and DPOSi as hole‐ and electron‐transporting layers, a high EQE of 27.5% and a maximum current efficiency of 49.4 cd A^?1 are achieved in the DCSPO/FIrpic doped device. Even at 10 000 cd m^?2, the efficiencies still remain 41.2 cd A^?1 and 23.0%, respectively.     

3D Printed Supercapacitor: Techniques,Materials, Designs,and Applications

Supercapacitors (SCs) offer broad possibilities in the rising domain of military and civilian owing to their intrinsic properties of superior power density, long lifetime, and safety features. Despite of low-cost, facile manufacture, and time-saving, 3D printing technology unleashes the potential of SCs in terms of achieving desirable capacitance with high mass loading, fabrication of well-designed complicated structures, and direct construction of on-chip integration systems. In this review, first, the representative printing technologies for SCs and advanced printable materials are scrutinized for SCs and advanced printable materials. Then the structure design principles of electrodes and devices are respectively highlighted and reported cases are systematically summarized. Next, configurations of the SCs and their applications in various areas are described in detail. Finally, the promising research directions for the future are discussed. The perspectives reviewed here are expected to provide a comprehensive understanding of 3D-printed SCs and guidance in realizing their promise in various applications.     

A Subtractive Photoresist Platform for Micro‐ and Macroscopic 3D Printed Structures

The selective removal of structural elements plays a decisive role in 3D printing applications enabling complex geometries. To date, the fabrication of complex structures on the microscale is severely limited by multistep processes. Herein, a subtractive photoresist platform technology that is transferable from microscopic 3D printing via direct laser writing to macroscopic structures via stereolithography is reported. All resist components are readily accessible and exchangeable, offering fast adaptation of the resist's property profile. The micro‐ and macroprinted structures can be removed in a facile fashion, without affecting objects based on standard photoresists. The cleavage is analyzed by time‐lapse optical microscopy as well as via in‐depth spectroscopic assessment. The mechanical properties of the printed materials are investigated by nanoindentation. Critically, the power of the subtractive resist platform is demonstrated by constructing complex 3D objects with flying features on the microscale.     

3D Fluorescent Hydrogel Origami for Multistage Data Security Protection

Current fluorescence‐based anti‐counterfeiting strategies primarily encode information onto single 2D planes and underutilize the possibility of encrypting data inside 3D structures to achieve multistage data security. Herein, a fluorescent‐hydrogel‐based 3D anti‐counterfeiting platform is demonstrated, which extends data encryption capability from single 2D planes to complex 3D hydrogel origami geometries. The materials are based on perylene‐tetracarboxylic‐acid‐functionalized gelatin/poly(vinyl alcohol) hydrogels, which simultaneously show Fe³⁺‐responsive fluorescence quenching, borax‐triggered shape memory, and self‐healing properties. By employing an origami technique, various complex 3D hydrogel geometries are facilely fabricated. On the basis of these results, a 3D anti‐counterfeiting platform is demonstrated, in which the data printed by using Fe³⁺ as the ink are safely protected inside complex 3D hydrogel origami structures. In this way, the encrypted data cannot be read until after specially predesigned procedures (both the shape recovery and UV light illumination actions), indicating higher‐level information security than the traditional 2D counterparts. This facile and general strategy opens up the possibility of utilizing 3D fluorescent hydrogel origami for data information encryption and protection.     

Controlled Mechanical Buckling for Origami‐Inspired Construction of 3D Microstructures in Advanced Materials

Origami is a topic of rapidly growing interest in both the scientific and engineering research communities due to its promising potential in a broad range of applications. Previous assembly approaches for origami structures at the micro/nanoscale are constrained by the applicable classes of materials, topologies, and/or capability for reversible control over the transformation process. Here, a strategy is introduced that exploits mechanical buckling for autonomic origami assembly of 3D structures across material classes from soft polymers to brittle inorganic semiconductors, and length scales from nanometers to centimeters. This approach relies on a spatial variation of thickness in the initial 2D structures as a means to produce engineered folding creases during the compressive buckling process. The elastic nature of the assembly scheme enables active, deterministic control over intermediate states in the 2D to 3D transformation in a continuous and reversible manner. Demonstrations include a broad set of 3D structures formed through unidirectional, bidirectional, and even hierarchical folding, with examples ranging from half cylindrical columns and fish scales, to cubic boxes, pyramids, starfish, paper fans, skew tooth structures, and to amusing system‐level examples of soccer balls, model houses, cars, and multifloor textured buildings.     

Bandgap Engineering of BiIns Nanowire for Wide-Spectrum,High-Responsivity,and Polarimetric-Sensitive Detection

Optical devices based on alloying semiconductors offer a plethora of new possibilities for detection across a broad spectrum. Among these devices, nanowire-based devices have gained much attention due to their remarkable specific surface area properties in terms of material synthesis, device structure, and performance. In this work, (Bi_xIn_1−x)₂S₃ nanowires are designed by controlling the ratio of Bi and In atoms. The atomic ratio directly affects the electronic band structure of the crystal, thereby further optimizing the performance of optoelectronic devices. According to the experimental results, Bi_1.28In_0.72S₃ nanowire-based photodetectors obtain the most excellent photoresponse performance. The typical device demonstrates a spectral response from deep ultraviolet (DUV 254 nm) to near-infrared (NIR 1064 nm) and achieves a maximum dichroic ratio of photoresponse of 1.5 under polarization-angle-sensitive detection in the 266–808 nm range. It also exhibits a photoresponse of 10.1 A W⁻¹ and a photodetectivity of 5.7 × 10¹⁰ Jones under 532 nm light irradiation. Additionally, the photodetector displays a fast response speed with a rise/fall time of 5/4.7 ms. Finally, “CSU” and puppy images produced by this device further demonstrate the effectiveness of alloying semiconductors in creating wide-spectrum, high-responsivity, fast-response, and polarimetric-sensitive photodetectors.