Simple Device Structure Research Articles

Mechanism Optimization of the Clamping and Cutting Arrangement Device for Solanaceae Scion and Stock Seedlings

Grafting is one of the main techniques used in intensive tomato cultivation to address abnormal weather, diseases, insect pests, and continuous cropping problems. In recent years, due to agricultural labor constraints, the industry has needed to make use of more machinery. In this study, a clamping and cutting arrangement device for Solanaceae scion and stock seedlings was developed; it included a UR5 robotic arm to realize the automatic clamping and cutting of multiple seedlings, to facilitate the mechanized grafting of seedlings. The clamping success rate of eggplant and tomato seedlings using this device was 99%. When working with four seedlings in a single operation, the oblique-cutting success rates for eggplant and tomato seedlings were 97.76% and 94.55%, respectively. Moreover, 404 eggplant seedlings and 384 tomato seedlings could be worked with in 1 h. After the splicing and grafting process had been completed, the survival rate of the grafted seedlings was 85%. The simple device structure could be used by the industry to assist operators in clipping and cutting seedlings, reduce the complexity of grafting operations, shorten training times, address the problem of labor constraints in Taiwan’s agricultural industry, and improve product quality and efficiency.

Spiral donor-based host materials for highly efficient blue thermally activated delayed fluorescence OLEDs

Spiral donor units have attracted extensive research focuses in designing highly emissive thermally activated delayed fluorescence (TADF) emitters. Herein, to reveal the significance of spiral donor units for constructing highly efficient host materials, several spiral donor-based host materials are developed. With the incorporation of spiral donor, increased intermolecular distance is achieved to reduce the concentration quenching effect of dopant. Moreover, the high triplet energy level of spiral donor can provide an additional energy transfer channel to further improve the device performance. Noteworthy, by connecting spiral donors or conventional carbazole unit with different electron-withdrawing units phenoxathiine 10,10-dioxide (PX) or phenoxathiine (PA), these hosts are given different photophysical properties of TADF, room-temperature phosphorescence (RTP) and conventional fluorescence (CF). The strong electron-withdrawing ability of PX is beneficial to the TADF character of spiral donor-based molecules, while the weak electron-withdrawing ability of PA is beneficial to the RTP property. Consequently, the blue OLEDs with DspiroAc-TRZ as a dopant emitter based on the hosts with TADF characters exhibit higher performance than those with RTP and CF properties, and excellent external quantum efficiency (EQE) of 36.1 % and current efficiency of 84.6 cd/A are achieved in a simple device structure. Furthermore, peak EQEs of 34.0 % and 33.0 % are achieved, when DspiroS-PX and DspiroS-PA hosted DspiroAc-TRZ are used to sensitize blue multi-resonance TADF emitter v-DABNA. Our work may shed new light on designing highly efficient host materials for TADF emitters.

2D Semiconductor Based Flexible Photoresponsive Ring Oscillators for Artificial Vision Pixels.

Artificial retina implantation provides an effective and feasible attempt for vision recovery in addition to retinal transplantation. The most advanced artificial retinas ever developed based on silicon technology are rigid and thus less compatible with the biosystem. Here we demonstrate flexible photoresponsive ring oscillators (PROs) based on the 2D semiconductor MoS2 for artificial retinas. Under natural light illuminations, arrayed PROs on flexible substrates serving as vision pixels can efficiently output light-intensity-dependent electrical pulses that are processable and transmittable in the human visual nerve system. Such PROs can work under low supply voltages below 1 V with a record-low power consumption, e.g. only 12.4 nW at a light intensity of 10 mW/cm2, decreased by ∼500 times compared with that of the state-of-the-art silicon devices. Such flexible artificial retinas with a simple device structure, high light-to-signal conversion efficiency, ultralow power consumption, and high tunability provide an alternative prosthesis for further clinical trials.

Colossal Vacancy Effect of 2D CuInP2S6 Quantum Dots for Enhanced Broadband Photodetection

Band engineering is an effective way to tune the physical and chemical properties of materials, leading to significant performance improvement. Herein, the first two-dimensional (2D) quaternary quantum dots (QDs), CuInP2S6 (CIPS) QDs, were successfully fabricated by the lithium intercalation method with a high yield of ∼29%. Importantly, the tuned band structure of CIPS was achieved by forming colossal lithium-induced phosphorus and sulfur vacancies, endowing CIPS QDs with stronger and broader optical absorbance, as well as higher conductivity. Therefore, CIPS QDs exhibit outstanding intrinsic optoelectronic performances toward broadband photodetection with a broadband photoresponse from 405 to 1550 nm, a photoresponsivity of 22.9 A/W, a detectivity of 3.65 × 108 Jones, and a response speed of 60 ms. Especially, such excellent performances can be realized in a simple device structure and ambient air, exceptionally different from most 2D QD-based photodetectors requiring a heterostructure, gate voltage, or vacuum condition. In addition, CIPS QDs retain outstanding photoresponse on curving flexible substrates and in imaging applications. This work provides a unique venue for band structure tuning to effectively manipulate materials’ optoelectronic properties and functionalities.

Carrier transport model of non-carrier-injection light-emitting diode

Non-carrier-injection light-emitting diodes (NCI-LEDs) are expected to be widely used in the next-generation micro-display technologies, including Micro-LEDs and nano-pixel light-emitting displays due to their simple device structures. However, because there is no external charge carrier injection, the internal carrier transport behavior of the NCI-LED cannot be described by using the traditional PN junction and LED theory. Therefore, establishing a carrier-transport model for the NCI-LED is of great significance in understanding its working mechanism and improving device performance. In this work, carrier transport mathematical model of the NCI-LED is established and the mechanical behavior of charge-carrier transport is analyzed quantitatively. Based on the mathematical model, the working mechanism of the NCI-LED is explained, the carrier transport characteristics of the device are obtained. Additionally, the key features, including the length of the induced charge region, the forward biased voltage across the internal PN junction, and the reverse biased voltage across the internal PN junction are studied. Their relationships with the applied frequency of the applied driving voltage are revealed. It is found that both the forward bias and reverse bias of the internal PN junction increase with the driving frequency. When the driving frequency reaches a certain value, the forward bias and the reverse bias of the PN junction will be maintained at a maximum value. Moreover, the length of the induced charge region decreases with the increase of the driving frequency, and when the frequency reaches a certain value, the induced charge region will always be in the state of exhaustion. According to the mathematical model, suggestions for the device optimization design are provided below. 1) Reducing the doping concentration of the induced charge region can effectively increase the voltage drop across the internal LED; 2) employing the tunneling effect occurring in the reverse-biased PN junction can effectively improve the electroluminescence intensity; 3) using the square-wave driving voltage can obtain a larger voltage drop across the internal LED and increase the electroluminescence intensity. This work on the carrier transport model is expected to e present a clear physical figure for understanding the working mechanism of NCI-LED, and to provide a theoretical guidance for optimizing the device structure.

Development status of inverted perovskite solar cells

While the population has exploded, the world's energy demand has also risen exponentially. Energy pollution is also very severe. Therefore, it is urgent to increase the utilization of renewable new energy. Solar power has the greatest potential in the new energy sources. One kind of solar cell is the inverted perovskite solar cell (I-PSC). It has the advantages of simple device structure, high absorption coefficient, small hysteresis effect, and good defect tolerance. In this paper, the effects of electron transfer, hole transportation and manufacturing technology on the appearance of inverted perovskite-type solar cells are discussed, also the foreground of their commercialization is presented. It is believed these processes are a small step for ameliorating the photoelectric conversion efficiency and stability of these devices.

Development of Efficient OLEDs from Solution Deposition.

The use of highly efficient organic emitters based on the thermally activated delayed fluorescence (TADF) concept is interesting due to their 100% internal quantum efficiency. Presented here is a solution deposition method for the fabrication of efficient organic light-emitting diodes (OLEDs) based on a TADF emitter in a simple device structure. This fast, low-cost, and efficient process can be used for all OLED emissive layers that follow the host-guest concept. The fundamental steps are described along with necessary information for further reproduction. The goal to establish a general protocol that can be easily adapted for principal organic emitters currently under study and development.

Digitally programmable organic light‐emitting tetrodes

AbstractLimited to the structure of traditional light‐emitting devices, electronic devices that can directly convert machine language into human visual information without introducing any back‐end circuit are still not easy to achieve. Based on a specially designed three‐phase co‐planar electrode structure, a new type of three‐phase alternating current driven organic light‐emitting device with the integration of emission and control functions, full‐color tunability and simple device structure is demonstrated in this study. We integrate the light‐emitting function of color‐tunable light‐emitting devices and the switching of three triodes in a single three phase organic light‐emitting device. The state control of luminous color and luminance intensity merely requires the introduction of a kind of machine language, that is an easy‐to‐program 6‐bit binary number coded digital signals. The color adjustable area covers 66% of the color triangle of the National Television System Committee. Such simple and easy‐to‐integrate light‐emitting system has great potential applications in the next‐generation man‐machine interface.

Triboelectric Nanogenerators: Enhancing Performance by Increasing the Charge-Generating Layer Compressibility.

Triboelectric nanogenerators (TENGs) have received significant attention for next-generation wearable electronics due to their simple device structure and low cost. Although the performance of TENGs is intimately tied to compressibility effects in the charge-generating layer, achieving high compressibility with conventional elastomers is challenging because molecular entanglements place a lower bound on the softness of cross-linked networks. Here, we demonstrate that bottlebrush elastomers are efficient charge-generating layers that improve the output performance of TENGs, including voltage, current, and surface potential, by minimizing entanglements and decreasing the compressive modulus (E). For example, a cross-linked bottlebrush with poly(dimethylsiloxane) side chains yielded TENGs with an output voltage (120 V) more than two times larger than a linear PDMS network (55 V). In conclusion, this study highlights the advantage of designing new charge-generating layers with improved compressibility to enhance TENG performance.

Interfacial Engineering for High‐Performance PTAA‐Based Inverted 3D Perovskite Solar Cells

In recent years, poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA)‐based inverted perovskite solar cells (IPSCs) have gained tremendous attention due to their simple device structure, easy fabrication process, and suitability for roll‐to‐roll process for fabricating flexible devices. With the recent years’ rapid progress, PTAA‐IPSCs have achieved higher efficiency than other IPSCs, revealing great potential for future applications. Among various strategies to enhance the performance of PTAA‐IPSCs, interfacial engineering has been highlighted with comprehensive merits, including improving the wettability of PTAA, enhancing the crystallinity of perovskite, modifying energy levels, and reducing defect traps at interfaces for enhancing charge transfer and reducing nonradiative recombination. Although extensive review articles have been published on PSCs, little attention has been focused on interfacial engineering of PTAA‐IPSCs. It is believed that it is of great importance to summarize the fruitful breakthroughs in recent years in this area and give some prospective. In this review, the development of PTAA‐IPSCs is summarized, and then interfacial engineering processes on perovskite, PTAA, and electron transport layer is systematically discussed, respectively. In addition, current challenges associated with the rapid developments in the field of PTAA‐IPSC have been pointed out and insightful outlooks for the future design and commercial development of PTAA‐IPSCs have been provided.

Natural biomaterial-based memristor bearing protonated polydopamine with enhanced bipolar resistive switching performance and environmental robustness

The searching for green memristor with good environmental robustness will be significant for next generation biodegradable devices. In this work, bio-compatible and non-toxic polydopamine (PDA) was prepared by self-polymerization of dopamine in simple aqueous solution, which was protonated by different acid concentrations (3–12 M HCl) and further fabricated as memory devices with structures of FTO/PDA/Ag. The ON/OFF ratio are enhanced gradually from 2.80 × 102 (PDA-3 M), 8.39 × 102 (PDA-6 M), 5.18 × 103 (PDA-9 M) to 2.41 × 104 (PDA-12 M). The lower conjugated degree, the closer lattice packing and the less radicals after acid treatment are the reasons for the enhanced bipolar resistive switching performances of protonated PDA-based memristor. The resistive switching mechanism is the conductive filament with three processes of Ohm, space charge limited conduction (SCLC) and trap-filled limited (TFL). In addition, the FTO/PDA-12 M/Ag exhibit good environmental robustness, including thermal (100 °C) and ionizing irradiation (UV exposure for 96 h). In all, the facial protonation treatment and the simple sandwich device structures together with good environmental robustness endow its promising applications in as green, stable and biodegradable next generation electron devices.

High Photocurrent Anisotropy in Domain‐Engineered Ferroelectrics for Visible‐Light Polarization Detection

AbstractVisible‐light polarization detection is a critical challenge for next‐generation light communication and imaging technologies. While low‐dimensional nanomaterials exhibit polarization‐dependent photocurrents originating from their anisotropic absorption, ferroelectric photovoltaics provide a photocurrent derived from spatial inversion symmetry breaking. Here, it is reported that domain‐engineered ferroelectrics are promising materials for visible‐light polarization detection. Polarization angle‐resolved photocurrent measurements demonstrate that the introduction of domain walls in ferroelectric BiFe0.95Mn0.05O3 films increases the photocurrent anisotropy ratio up to 7.9 under visible light with hν = 2.4 eV (λ = 515 nm), which is much higher than that of typical nanomaterials (≈2–3). Simulations of polarization‐dependent photocurrents show that the domain walls provide an additional degree of freedom for designing ferroelectrics with quite high photocurrent anisotropy. This study opens up the possibility of developing ferrophotovoltaic‐based visible‐light polarization detectors with simple device structures.

Achieving Solution-Processed Non-Doped Single-Emitting-Layer White Organic Light-Emitting Diodes through Adjusting Pyrene-Based Polyaromatic Hydrocarbon.

Single-emitting-layer white organic light-emitting diodes (SEL-WOLEDs) have developed rapidly in recent years due to the outstanding advantages of high efficiency, simple device structure, low cost, less phase separation, and stable emission color. Nevertheless, the relatively complicated host-dopant system is usually essential for most previous SEL-WOLEDs and the development of simple non-doped SEL-WOLEDs lags behind. Hence the straightforward synthesis of single-white-emitting molecules for non-doped SEL-WOLEDs still remains a great challengeable task. In this article, we designed and synthesized two new pyrene-based polyaromatic hydrocarbons (PAHs) and used them as emitting layer materials in the OLED devices. When the molecules change from the mono-fused one to bis-fused one, the emitting light changes from greenish to white color. Further study indicated that the bis-fused molecule PyD with more twisted and extended backbone packed in neat Cmca space group in single-crystal system compared with P21 /n for PyS, which may be favorable to form excimers in the solid state and broaden the emission spectrum in the OLEDs. As a result, a solution-processed non-doped single-white-emitting-molecule SEL-WOLED with high performance (e. g., a high color rendering index of 66) is reported. The findings will be beneficial not only to further development of simple WOLEDs, but also to other related organic optoelectronic technology.

Tough, flexible, and durable all-polyampholyte hydrogel supercapacitor

Most of the currently developed flexible energy storage devices lack sufficient flexibility to withstand various deformations, such as stretching, compression, and bending under the action of external forces. It also lacks sufficient and stable energy output. In this work, we use the flexible material hydrogel as electrode and electrolyte to design an all-hydrogel integrated flexible supercapacitor. Both the electrode and the electrolyte contain the same polyampholyte hydrogel P(NaSS-co-DMAEA-Q) matrix, making them possess superb self-adhesion due to the electrostatic interaction between the anion and cation group, and highly softness/toughness thanks to the energy-dissipative mechanism. The electrode of supercapacitor is a composite of activated carbon and hydrogel, which has excellent mechanical and electrical properties. Supercapacitors prepared from hydrogel electrodes and hydrogel electrolytes are inherently scalable/compressible, and simultaneously deliver high areal capacitance (128.9 mF cm−2 at 1 mV s−1 and 340.18 mF cm−2 at 0.1 mA cm−2) and maintain stable energy output. The combination of simple device structure, stable mechanical properties and excellent electrical properties makes flexible supercapacitors promising for applications in wearable electronics/devices and energy storage.

In2O3/g-C3N4/Au ternary heterojunction-integrated surface plasmonic and charge-separated effects for room-temperature ultrasensitive NO2 detection

Light-activated gas sensors based on semiconducting metal oxides (SMOs) hold great promise for next-generation gas sensing application, due to their unique superiority including room-temperature operation, intrinsic safety, and simple device structure. However, poor visible-light absorption and fast carrier recombination of SMOs sensing film are two main barriers that seriously restrict their sensing performance of light-activated gas sensors. Herein, a visible-light activated gas sensor based on Au nanoparticles modified In2O3/g-C3N4 heterojunction nanofibers is developed. Excellent sensing response (Rg/Ra = 17.2 to 1 ppm NO2, where Ra and Rg represent the resistance of sensors when exposed to air or target gas) and fast response/recovery kinetics at room temperature are obtained, which is markedly better than the sensors based on pristine In2O3 nanofibers and In2O3/g-C3N4 nanofibers. Through the discussion and estimation of experimental results, the improved gas sensing properties of In2O3/g-C3N4/Au-based sensors are speculated to be related to the enhanced visible light utilization benefiting from localized surface plasmon resonance (LSPR) effect of Au nanoparticles, and the efficient separation of photo-generated carriers enabled by heterojunctions between In2O3, Au, and g-C3N4 components. The current work will provide a universal strategy to develop high-performance light-activated gas sensor and a deep understanding about the sensing principle of this novel type of gas sensor.

Electrochemical Sensor Applications of Nanoparticle Modified Carbon Paste Electrodes to Detect Various Neurotransmitters: A Review

Neurotransmitters are synapses transmitting messengers that are vital towards human wellness. Any abnormality in their behaviour can lead to huge psychological ailments such as Parkinson's, Alzheimer's, and Schizophrenia. During diagnosing and assessing mental diseases, it is critical to discover distinct measures of different neurotransmitters present. A combination of nanomaterials, proteins, and polymers are employed to create suitable detecting and sensing component systems. Electrochemical detection has been widely employed for in-vivo detection, with FSCV emerging as the most promising technology to date due to advantages such as high sensitivities, simple device structure, and facile downsizing. Excessive background noise and signal, restricted target selectivity, declination with time, and the device fouling are all issues that in-vivo electrochemical neurotransmitter indications encounter. Nanomaterials have sparked a tremendous focus in recent years owing to their diverse properties. CPEs are amongst the safest and most ecologically beneficial electrodes with a vast scope of applications due to their incredibly simple and rapid manufacturing method, lower back - ground current, relatively inexpensive, adaptability to numerous modifiers and modifying techniques, so on and so forth.

High-performance CsGeBr3 perovskite/ WS2 Nano-Flakes Field-Effect Transistor at high temperature

This study explores the current-voltage characterization of tungsten disulfide Nano-Flakes (WS2 NFs) Field-Effect-Transistor (FET) under various temperatures with a simple back-gate device structure. Due to the non-toxic nature of inorganic perovskite CsGeBr3 (CGB), this material is applied to fabricate a CGB/WS2 FET by drop-casting of lead-free perovskite CGB on the WS2 NFs FET. The characterization of fabricated two FET devices has been performed under the illumination of a laser source (at a wavelength of ∼532 nm) with three different temperatures (298°, 313°, and 333° K). The output and transfer characteristics of CsGeBr3/WS2 NFs FET illustrate that CGB is very effective in boosting the photocurrent and performance of the FET. For each two FET devices, increasing the temperature led to a decrease in drain-source current (Ids), whereas the rate of Ids reduction in CGB/WS2 NFs FET is roughly two times less than WS2 NFs FET. The results demonstrate that the conductivity and Ids of the CGB/WS2 NFs FET have been doubled compared to the bare WS2-NFs FET. Most importantly, the CGB/WS2 NFs FET shows higher external quantum efficiency, photo-responsivity, and detectivity in comparison with the WS2 NFs FET. The superior photo-sensing properties of the CGB/WS2 NFs FET are very promising to extend the two-dimensional optoelectronic devices with excellent performance.

Doubling and tripling the absorption peaks of a multi-band graphene terahertz absorber

Tunable terahertz (THz) absorber is a hot research topic in recent years. However, absorption peak number control is rarely studied. A multi-band THz absorber based on a horizontal array of vertically offset graphene nanoribbon pairs is proposed and numerically investigated. By asymmetrically widening the lower layer graphene nanoribbons, two new absorption peaks are added due to the effective excitations of even-mode lateral Fabry-Perot resonances. By different Fermi energy applying strategies, doubling and tripling of the absorption peak number can be realized. Besides, the relatively simple device structure reduces the difficulty of subsequent fabrications. The proposed peak number controllable multi-band THz absorber shows promise in the areas of sensing, non-destructive testing, explosive detection and etc.

Ammonia sensing characteristics of a cerium oxide thin film coated with platinum nanoparticles

This paper reports on ammonia (NH3) sensing characteristics of a new semiconducting metal oxide (SMO) sensor. employing a cerium oxide (CeO2) thin film and platinum (Pt) nanoparticles (NPs) as a sensing layer. The thickness of CeO2 thin film is 30 nm and the particle size of Pt NPs is about 4–6 nm. Based on the enhanced surface area/volume (SA/V) ratio and catalytic ability of Pt metal, the sensing behaviors are efficiently improved owing to the smaller Pt NPs. A high sensing response of 5.81 under 1000 ppm NH3/air gas and a low detectable content of 1 ppm NH3/air are acquired at 275 ℃. In addition, a relatively fast sensing action with the response (recovery) times of 15 s (85 s) and 6 s (25 s) are observed upon exposure to 1000 and 1 ppm NH3/air gas, respectively, at 300 ℃. The Langmuir isotherm is used to study the related surface coverage under introduced ammonia gas. The proposed Pt NP/CeO2 sensor shows prominent stability for long-term operation without intentional passivation treatment. The proposed sensor device’s benefits include a simple device structure, relatively easy manufacturing, a wide sensing range of ammonia gas content (1–1000 ppm NH3/air), and lower cost.

Colloidal MoS2 quantum dots for high-performance low power resistive memory devices with excellent temperature stability

Conventional memory technologies are facing enormous problems with downscaling, and are hence unable to fulfill the requirement of big data storage generated by a huge explosion of digital information. A resistive random access memory device (RRAM) is one of the most emerging technologies for next-generation computing data storage owing to its high-density stacking, ultrafast switching speed, high non-volatility, multilevel data storage, low power consumption, and simple device structure. In this work, colloidal MoS2 quantum dots (QDs) embedded in an insulating matrix of poly-(4vinylpyridine) (PVP) were used as an active layer to fabricate a RRAM device. The MoS2 QDs-PVP based RRAM device reveals an excellent nonvolatile resistive switching (RS) behavior with a maximum current on-off ratio (ION/IOFF) of 105. High endurance, long retention time, and successive “write-read-erase-read” cycles indicate high-performance RRAM characteristics. The ultimate power consumption by this RRAM device is considerably low for energy saving. In addition, the MoS2 QDs-PVP based device shows RS behavior even at 130 °C. High ION/IOFF, low operating power, high endurance, long retention time, and excellent stability with temperatures reveal that the MoS2 QDs-PVP based device can be a promising candidate for high-performance low power RRAM devices that can be operated at relatively higher temperatures.