Plasmonic Enhanced Optoelectronic Devices

Plasmonic metal nanostructures have recently attracted extensive research and developed into a promise approach for enhancing the performance of various optoelectronic devices. This brief article reviews recent research advances on the plasmonic enhanced optoelectronic devices and highlights a variety of strategies of incorporating plasmonic nanostructures into different optoelectronics such as solar cells, light-emitting diode, and multicolor photodetector, etc. In addition, the benefits of using various plasmonic metal nanostructures are discussed and the resulting enhancement mechanisms are displayed and summarized.     

From Pb to Bi: A Promising Family of Pb‐Free Optoelectronic Materials and Devices

Lead‐based organic–inorganic hybrid perovskite materials are widely used in optoelectronic devices due to their excellent photophysical properties. However, the main issues which hinder its commercialization are the toxicity caused by lead and the intrinsic instability of the material. Recently, many lead‐free halide materials with good intrinsic stability have been reported, among which bismuth‐based halide materials have attracted extensive research due to their structure and promising optoelectronic properties. In this review, bismuth‐based materials are divided into binary BiX₃ (X = I, Br, Cl), ternary A_aBi_bX_a+3b (A = Cs, Rb, MA, Ag, etc.), and quaternary A₂AgBiX₆ (A = Cs, Rb, MA, etc.) according to its elemental composition. The structure and optoelectronic properties of bismuth‐based halide materials, which may be helpful for the development of bismuth‐based halide materials and lead‐free perovskites in the future, are summarized and highlighted.     

The Rise of Textured Perovskite Morphology: Revolutionizing the Pathway toward High‐Performance Optoelectronic Devices

Halide perovskite materials have achieved overwhelming success in various optoelectronic applications, especially perovskite solar cells and perovskite‐based light‐emitting diodes (P‐LEDs), owing to their outstanding optical and electric properties. It is widely believed that flat and mirror‐like perovskite films are imperative for achieving high device performance, while the potential of other perovskite morphologies, such as the emerging textured perovskite, is overlooked, which leaves plenty of room for further breakthroughs. Compared to flat and mirror‐like perovskites, textured perovskites with unique structures, e.g., coral‐like, maze‐like, column‐like or quasi‐core@shell assemblies, are more efficient at light harvesting and charge extraction, thus revolutionizing the pathways toward ultrahigh performance in perovskite‐based optoelectronic devices. Employing a textured perovskite morphology, the record of external quantum efficiency for P‐LEDs is demonstrated as 21.6%. In this research news, recent progress in the utilization of textured perovskite is summarized, with the emphasis on the preparation strategies and prominent optoelectronic properties. The impact of the textured morphology on light harvesting, carrier dynamic management, and device performance is highlighted. Finally, the challenges and great potential of employing these innovative morphologies in fabricating more efficient optoelectronic devices, or creating a new energy harvesting and conversion regime are also provided.     

Nanobiohybrid Material‐Based Bioelectronic Devices

Biomolecules, especially proteins and nucleic acids, have been widely studied to develop biochips for various applications in scientific fields ranging from bioelectronics to stem cell research. However, restrictions exist due to the inherent characteristics of biomolecules, such as instability and the constraint of granting the functionality to the biochip. Introduction of functional nanomaterials, recently being researched and developed, to biomolecules have been widely researched to develop the nanobiohybrid materials because such materials have the potential to enhance and extend the function of biomolecules on a biochip. The potential for applying nanobiohybrid materials is especially high in the field of bioelectronics. Research in bioelectronics is aimed at realizing electronic functions using the inherent properties of biomolecules. To achieve this, various biomolecules possessing unique properties have been combined with novel nanomaterials to develop bioelectronic devices such as highly sensitive electrochemical‐based bioelectronic sensing platforms, logic gates, and biocomputing systems. In this review, recently reported bioelectronic devices based on nanobiohybrid materials are discussed. The authors believe that this review will suggest innovative and creative directions to develop the next generation of multifunctional bioelectronic devices.     

Organic Field‐Effect Transistor for Energy‐Related Applications: Low‐Power‐Consumption Devices,Near‐Infrared Phototransistors,and Organic Thermoelectric Devices

The organic field‐effect transistor (OFET) is the basic building block of integrated circuits. The charge carrier mobility and operating frequency of OFETs have continued to increase; therefore, the power dissipation of OFETs can no longer be ignored. Many research efforts have been made to develop low‐power‐consumption OFETs and complementary circuits. Despite the switching function, OFETs can also be utilized in emerging energy‐related applications, such as near‐infrared (NIR) photodetectors and organic thermoelectric devices. Organic phototransistors show considerably higher photo responsivity than other photodetector architectures due to field‐effect charge modulation. The photoinduced gate modulating largely suppresses the dark current while simultaneously providing gain. These characteristics may favor NIR light detection and suggest that the organic phototransistor is a promising candidate for optoelectronic applications in the NIR regime. For organic thermoelectric applications, OFETs can work as a powerful tool for examining the charge and energy transport in the organic semiconductor, thus giving insight into organic thermoelectric studies. In this review, the authors highlight recent advances in OFET‐ related energy topics, including low‐power‐consumption OFETs, NIR photodetectors, and organic thermoelectric devices. The remaining challenges in the field will also be discussed.     

Nature‐Inspired Electrochemical Energy‐Storage Materials and Devices

Currently, tremendous efforts are being devoted to develop high‐performance electrochemical energy‐storage materials and devices. Conventional electrochemical energy‐storage systems are confronted with great challenges to achieve high energy density, long cycle‐life, excellent biocompatibility and environmental friendliness. The biological energy metabolism and storage systems have appealing merits of high efficiency, sophisticated regulation, clean and renewability, and the rational design and fabrication of advanced electrochemical energy‐storage materials and smart devices inspired by nature have made some breakthrough progresses, recently. In this review, we summarize the latest developments in the field of nature‐inspired electrochemical energy‐storage materials and devices. Specifically, the nature‐inspired exploration, preparation and modification of electrochemical energy‐storage related materials including the active materials, binders, and separators are introduced. Furthermore, nature‐inspired design and fabrication of smart energy‐storage devices such as self‐healing supercapacitors, supercapacitors with ultrahigh operating voltage, and self‐rechargeable batteries are also discussed. The review aims to provide insights and expanded research perspectives for further study in this exciting field based on our comprehensive discussions.     

Textile‐Based Electrochemical Energy Storage Devices

In the past few years, insensitive attentions have been drawn to wearable and flexible energy storage devices/systems along with the emergence of wearable electronics. Much progress has been achieved in developing flexible electrochemical energy storage devices with high end‐use performance. However, challenges still remain in well balancing the electrochemical properties, mechanical properties, and the processing technologies. In this review, a specific perspective on the development of textile‐based electrochemical energy storage devices (TEESDs), in which textile components and technologies are utilized to enhance the energy storage ability and mechanical properties of wearable electronic devices, is provided. The discussion focuses on the material preparation and characteristics, electrode and device fabrication strategies, electrochemical performance and metrics, wearable compatibility, and fabrication scalability of TEESDs including textile‐based supercapacitors and lithium‐ion batteries.     

High‐Performance GeTe‐Based Thermoelectrics: from Materials to Devices

High‐performance GeTe‐based thermoelectrics have been recently attracting growing research interest. Here, an overview is presented of the structural and electronic band characteristics of GeTe. Intrinsically, compared to low‐temperature rhombohedral GeTe, the high‐symmetry and high‐temperature cubic GeTe has a low energy offset between L and Σ points of the valence band, the reduced direct bandgap and phonon group velocity, and as a result, high thermoelectric performance. Moreover, their thermoelectric performance can be effectively enhanced through either carrier concentration optimization, band structure engineering (bandgap reduction, band degeneracy, and resonant state engineering), or restrained lattice thermal conductivity (phonon velocity reduction or phonon scattering). Consequently, the dimensionless figure of merit, ZT values, of GeTe‐based thermoelectric materials can be higher than 2. The mechanical and thermal stabilities of GeTe‐based thermoelectrics are highlighted, and it is found that they are suitable for practical thermoelectric applications except for their high cost. Finally, it is recognized that the performance of GeTe‐based materials can be further enhanced through synergistic effects. Additionally, proper material selection and module design can further boost the energy conversion efficiency of GeTe‐based thermoelectrics.     

Recent Advances in Nanogenerator‐Driven Self‐Powered Implantable Biomedical Devices

Implantable medical devices (IMDs) have experienced a rapid progress in recent years to the advancement of state‐of‐the‐art medical practices. However, the majority of this equipment requires external power sources like batteries to operate, which may restrict their application for in vivo situations. Furthermore, these external batteries of the IMDs need to be changed at times by surgical processes once expired, causing bodily and psychological annoyance to patients and rising healthcare financial burdens. Currently, harvesting biomechanical energy in vivo is considered as one of the most crucial energy‐based technologies to ensure sustainable operation of implanted medical devices. This review aims to highlight recent improvements in implantable triboelectric nanogenerators (iTENG) and implantable piezoelectric nanogenerators (iPENG) to drive self‐powered, wireless healthcare systems. Furthermore, their potential applications in cardiac monitoring, pacemaker energizing, nerve‐cell stimulating, orthodontic treatment and real‐time biomedical monitoring by scavenging the biomechanical power within the human body, such as heart beating, blood flowing, breathing, muscle stretching and continuous vibration of the lung are summarized and presented. Finally, a few crucial problems which significantly affect the output performance of iTENGs and iPENGs under in vivo environments are addressed.     

Paper‐Based Energy‐Storage Devices Comprising Carbon Fiber‐Reinforced Polypyrrole‐Cladophora Nanocellulose Composite Electrodes

Composites of polypyrrole (PPy) and Cladophora nanocellulose, reinforced with 8 μm‐thick chopped carbon filaments, can be used as electrode materials to obtain paper‐based energy‐storage devices with unprecedented performance at high charge and discharge rates. Charge capacities of more than 200 C g^?1 (PPy) are obtained for paper‐based electrodes at potential scan rates as high as 500 mV s^?1, whereas cell capacitances of ～60–70 F g^?1 (PPy) are reached for symmetric supercapacitor cells with capacitances up to 3.0 F (i.e.,0.48 F cm^?2) when charged to 0.6 V using current densities as high as 31 A g^?1 based on the PPy weight (i.e., 99 mA cm^?2). Energy and power densities of 1.75 Wh kg^?1 and 2.7 kW kg^?1, respectively, are obtained when normalized with respect to twice the PPy weight of the smaller electrode. No loss in cell capacitance is seen during charging/discharging at 7.7 A g^?1 (PPy) over 1500 cycles. It is proposed that the nonelectroactive carbon filaments decrease the contact resistances and the resistance of the reduced PPy composite. The present straightforward approach represents significant progress in the development of low‐cost and environmentally friendly paper‐based energy‐storage devices for high‐power applications.     

2D Materials for Large‐Area Flexible Thermoelectric Devices

The rapid development of the concept of the “Internet of Things (IoT)” requires wearable devices with maintenance‐free batteries, and thermoelectric energy conversion based on large‐area flexible materials has attracted much attention. Among large‐area flexible materials, 2D materials, such as graphene and related materials, are promising for thermoelectric applications due to their excellent transport properties and large power factors. In this Review, both single‐crystalline and polycrystalline 2D materials are surveyed using the experimental reports on thermoelectric devices of graphene, black phosphorus, transition metal dichalcogenides, and other 2D materials. In particular, their carrier‐density dependent thermoelectric properties and power factors maximized by Fermi level tuning techniques are focused. The comparison of the relevant performances between 2D materials and commonly used thermoelectric materials reveals the significantly enhanced power factors in 2D materials. Moreover, the current progress in thermoelectric module applications using large‐area 2D material thin films is summarized, which consequently offers great potential for the use of 2D materials in large‐area flexible thermoelectric device applications. Finally, important remaining issues and future perspectives, such as preparation methods, thermal transports, device designs, and promising effects in 2D materials, are discussed.