High-performance Electronics Research Articles

Eco-Friendly Boost for Perovskite Photovoltaics: Harnessing Cellulose-Modified SnO2 as a High-Performance Electron Transporting Material.

In this study, a passivated tin oxide (SnO2) film is successfully obtained through the implementation of sodium carboxymethyl cellulose (Na-CMC) modifier agent and used as the electron transporting layer (ETL) within the assembly of perovskite solar cells (PSCs). The strategic incorporation of the Na-CMC modifier agent yields discernible enhancements in the optoelectronic properties of the ETL. Among the fabricated cells, the champion cell based on Na-CMC-complexed SnO2 ETL achieves a conversion efficiency of 22.2% with an open-circuit voltage (VOC) of 1.12 V, short-circuit current density (JSC) of 24.57 mA/cm2, and fill factor (FF) of 80.6%. On the other hand, these values are measured for the pristine SnO2 ETL-based control cell as VOC = 1.11 V, JSC = 23.59 mA/cm2, and FF = 76.7% with an efficiency of 20.1%. This improvement can be ascribed to the high charge extraction ability, higher optical transmittance, better conductivity, and decrease in the trap state density associated with the passivated ETL structure. In addition, the cells employing Na-CMC-complexed SnO2 ETL exhibit prolonged stability under ambient conditions during 2000 h. Based on the preliminary results, this study also presents a set of findings that could have substantial implications for the potential use of the Na-CMC molecule in both large-scale perovskite cells and perovskite/Si tandem configuration.

Over 5 × 103-Fold Enhancement of Responsivity in Ga2O3-Based Solar Blind Photodetector via Acousto-Photoelectric Coupling.

The emergence of the wide-band-gap semiconductor Ga2O3 has propelled it to the forefront of solar blind detection activity owing to its key features. Although various architectures and designs of Ga2O3-based solar blind photodetectors have been proposed, their performance still falls short of commercial standards. In this study, we demonstrate a method to enhance the performance of a simple metal-semiconductor-metal-structured Ga2O3-based solar blind photodetector by exciting acoustic surface waves. Specifically, we demonstrate that under a bias voltage of 100 mV and a radio frequency signal of 20 dBm, the responsivity and detectivity can increase from 2.78 to 1.65 × 104 A/W and from 8.35 × 1014 to 2.66 × 1016 jones, respectively, rivaling a commercial photomultiplier tube. The over 5 × 103-fold enhancement in responsivity could be attributed to the acousto-photoelectric coupling mechanism. Furthermore, since surface acoustic waves can also serve as signal receivers, such photodetectors offer the prospect of dual-mode detection. Our findings reveal a promising pathway for achieving high-performance Ga2O3-based electronics and optoelectronics.

Universal selective transfer printing via micro-vacuum force

Transfer printing of inorganic thin-film semiconductors has attracted considerable attention to realize high-performance soft electronics on unusual substrates. However, conventional transfer technologies including elastomeric transfer printing, laser-assisted transfer, and electrostatic transfer still have challenging issues such as stamp reusability, additional adhesives, and device damage. Here, a micro-vacuum assisted selective transfer is reported to assemble micro-sized inorganic semiconductors onto unconventional substrates. 20 μm-sized micro-hole arrays are formed via laser-induced etching technology on a glass substrate. The vacuum controllable module, consisting of a laser-drilled glass and hard-polydimethylsiloxane micro-channels, enables selective modulation of micro-vacuum suction force on microchip arrays. Ultrahigh adhesion switchability of 3.364 × 106, accomplished by pressure control during the micro-vacuum transfer procedure, facilitates the pick-up and release of thin-film semiconductors without additional adhesives and chip damage. Heterogeneous integration of III-V materials and silicon is demonstrated by assembling microchips with diverse shapes and sizes from different mother wafers on the same plane. Multiple selective transfers are implemented by independent pressure control of two separate vacuum channels with a high transfer yield of 98.06%. Finally, flexible micro light-emitting diodes and transistors with uniform electrical/optical properties are fabricated via micro-vacuum assisted selective transfer.

Controllable electrical characteristic of Ti3C2T2/MoS2 (T = OH, F, O) interfaces for high performance electronics: Insights from first-principles

Two-dimensional (2D) semiconductors have shown competitive potential for applications into beyond‑silicon electronics. However, the controllable electrical characteristic of metal-semiconductor interfaces is still a challenge for high performance electronics due to Fermi level pinning. To explore Ti3C2T2/MoS2 (T = OH, F, O) for high performance electronics, the vertical electric field and interlayer distance are adopted here to regulate the electrical characteristic of interfaces based on the first-principles calculations. Though this, the electrical characteristic of Ti3C2O2/MoS2 and Ti3C2F2/MoS2 are more sensitive to electric field or interlayer distance than that of Ti3C2(OH)2/MoS2. Especially, the negative electric field with larger than −0.2 V/Å makes Ti3C2O2/MoS2 interface change from p-type Schottky to n-type Schottky contact. Furthermore, the Ti3C2O2/MoS2 interface can not only switch from p-type Schottky to n-type Schottky contact, but also from p-type Schottky to p-type Ohmic contact by varying interlayer distance. Moreover, the tunneling barriers of all interfaces are more sensitive to interlayer distance than to electric field. This work provides vital insights for high-performance electronics of Ti3C2T2/MoS2 (T = OH, F, O) in experiments.

Enhancing the Carrier Transport in Monolayer MoS2 through Interlayer Coupling with 2D Covalent Organic Frameworks.

The coupling of different 2D materials (2DMs) to form van der Waals heterostructures (vdWHs) is a powerful strategy for adjusting the electronic properties of 2D semiconductors, for applications in opto-electronics and quantum computing. 2D molybdenum disulfide (MoS2 ) represents an archetypical semiconducting, monolayer thick versatile platform for the generation of hybrid vdWH with tunable charge transport characteristics through its interfacing with molecules and assemblies thereof. However, the physisorption of (macro)molecules on 2D MoS2 yields hybrids possessing a limited thermal stability, thereby jeopardizing their technological applications. Herein, the rational design and optimized synthesis of 2D covalent organic frameworks (2D-COFs) for the generation of MoS2 /2D-COF vdWHs exhibiting strong interlayer coupling effects are reported. The high crystallinity of the 2D-COF films makes it possible to engineer an ultrastable periodic doping effect on MoS2 , boosting devices' field-effect mobility at room temperature. Such a performance increase can be attributed to the synergistic effect of the efficient interfacial electron transfer process and the pronounced suppression of MoS2 's lattice vibration. This proof-of-concept work validates an unprecedented approach for the efficient modulation of the electronic properties of 2D transition metal dichalcogenides toward high-performance (opto)electronics for CMOS digital circuits.

Grain refinement and high-frequency properties of spark plasma sintered MnZn ferrite

MnZn soft magnetic ferrites are essential materials for energy conversion in power electronics. The rapid development of miniaturized and energy-saving electronics has put forth an urgent need for high-frequency MnZn ferrites. However, the current MnZn ferrites suffer from a rapid decline of permeability and a drastic increase in power loss at frequencies above 5 MHz, which severely limits their use in high-frequency power electronics. In this study, the Spark Plasma Sintering (SPS) technology was used to prepare high-frequency MnZn ferrites. Compared to samples prepared by traditional solid-state sintering, SPS ferrite exhibits superior high-frequency properties with cut-off frequency of 57 MHz, and a power loss of 169.6 kW/m3 at 20 MHz. The improved high-frequency performance is due to the monodomain structure which is induced by grain refinement via spark plasma sintering. This study presents an effective method for manufacturing high-frequency soft magnetic ferrite and will promote the development of high-performance power electronics.

A High-Performance InGaAs Vertical Electron-Hole Bilayer Tunnel Field Effect Transistor with P+-Pocket and InAlAs-Block.

To give consideration to both chip density and device performance, an In0.53Ga0.47As vertical electron-hole bilayer tunnel field effect transistor (EHBTFET) with a P+-pocket and an In0.52Al0.48As-block (VPB-EHBTFET) is introduced and systematically studied by TCAD simulation. The introduction of the P+-pocket can reduce the line tunneling distance, thereby enhancing the on-state current. This can also effectively address the challenge of forming a hole inversion layer in an undoped InGaAs channel during device fabrication. Moreover, the point tunneling can be significantly suppressed by the In0.52Al0.48As-block, resulting in a substantial decrease in the off-state current. By optimizing the width and doping concentration of the P+-pocket as well as the length and width of the In0.52Al0.48As-block, VPB-EHBTFET can obtain an off-state current of 1.83 × 10-19 A/μm, on-state current of 1.04 × 10-4 A/μm, and an average subthreshold swing of 5.5 mV/dec. Compared with traditional InGaAs vertical EHBTFET, the proposed VPB-EHBTFET has a three orders of magnitude decrease in the off-state current, about six times increase in the on-state current, 81.8% reduction in the average subthreshold swing, and stronger inhibitory ability on the drain-induced barrier-lowering effect (7.5 mV/V); these benefits enhance the practical application of EHBTFETs.

Membrane-encapsulated, moisture-desorptive passive cooling for high-performance, ultra-low-cost, and long-duration electronics thermal management

Membrane-encapsulated, moisture-desorptive passive cooling for high-performance, ultra-low-cost, and long-duration electronics thermal management

Breaking the Trade-Off Between Polymer Dielectric Constant and Loss via Aluminum Oxo Macrocycle Dopants for High-Performance Neuromorphic Electronics.

The dielectric layer is crucial in regulating the overall performance of field-effect transistors (FETs), the key component in central processing units, sensors, and displays. Despite considerable efforts being devoted to developing high-permittivity (k) dielectrics, limited progress is made due to the inherent trade-off between dielectric constant and loss. Here, a solution is presented by designing a monodispersed disk-shaped Ce-Al-O-macrocycle as a dopant in polymer dielectrics. The molecule features a central Ce(III) core connected with eight Al atoms through sixteen bridging hydroxyls and eight 3-aminophenyl peripheries. The incorporation of this macrocycle in polymer dielectrics results in an up to sevenfold increase in dielectric constants and up to 89% reduction in dielectric loss at low frequencies. Moreover, the leakage-current densities decrease, and the breakdown strengths are improved by 63%. Relying on the above merits, FETs bearing cluster-doped polymer dielectrics give near three-orders source-drain current increments while maintaining low-level leakage/off currents, resulting in much higher charge-carrier mobilities (up to 2.45cm2 V-1 s-1 ) and on/off ratios. This cluster-doping strategy is generalizable and shows great promise for ultralow-power photoelectric synapses and neuromorphic retinas. This work successfully breaks the trade-off between dielectric constant and loss and offers a unique design for polymer composite dielectrics.

Achieving Ideal and Environmentally Stable n-Type Charge Transport in Polymer Field-Effect Transistors.

Realizing ideal charge transport in field-effect transistors (FETs) of conjugated polymers is crucial for evaluating device performance, such as carrier mobility and practical applications of conjugated polymers. However, the current FETs using conjugated polymers as the active layers generally show certain non-ideal transport characteristics and poor stability. Here, ideal charge transport of n-type polymer FETs is achieved on flexible polyimide substrates by using an organic-inorganic hybrid double-layer dielectric. Deposited conjugated polymer films show highly ordered structures and low disorder, which are supported by grazing-incidence wide-angle X-ray scattering, near-edge X-ray absorption fine structure, and molecular dynamics simulations. Furthermore, the organic-inorganic hybrid double-layer dielectric provides low interfacial defects, leading to excellent charge transport in FETs with high electron mobility (1.49 ± 0.46 cm2V-1s-1) and ideal reliability factors (102 ± 7%). Fabricated polymer FETs show a self-encapsulation effect, resulting in high stability of the FET charge transport. The polymer FETs still work with high mobility above 1 cm2V-1s-1 after storage in air for more than 300 days. Compared with state-of-the-art conjugated polymer FETs, this work simultaneously achieves ideal charge transport and environmental stability in n-type polymer FETs, facilitating rapid device optimization of high-performance polymer electronics.

Breakup-Free and Colorful Liquid Metal Thin Films via Electrochemical Oxidation.

Thin-film metal conductors featuring high conductivity and stretchability are basic building blocks for high-performance conformable electronics. Gallium-based liquid metals are attractive candidates for thin-film conductors due to their intrinsic stretchability and ease of processing. Moreover, the phase change nature of liquid metal provides an opportunity to create conformal electronics in a substrate-free manner. However, thin liquid metal films tend to break during the solid-to-liquid transition due to the high surface tension of liquid metal. Here, we created breakup-free liquid metal thin films by the electrochemical oxidation of solid gallium films. We show that electrochemical oxidation can enhance the mechanical strength of the gallium oxide layer and its interfacial adhesion to the gallium core. When heated to the liquid state, the oxidized gallium films can maintain their structural integrity on various solid substrates, hydrogels, and even the water surface. The solid-liquid phase change-induced stiffness decrease allowed the gallium films to be conformably attached to various nonplanar surfaces upon heating or water transfer printing. Moreover, we also found that enhanced electrochemical oxidation can result in the formation of structure color due to nanoporous structures on the film surface. We also demonstrate the applications of oxidized liquid metal films in functional electronics, electrophysiological monitoring, and tattoo art.

Near-infrared tunable Tamm plasmons high-performance hot electron photodetector based on Ag/Ge2Sb2Te5 low Schottky barrier

Hot electron photodetector is a typical hot electron optoelectronic device, which can realize the narrow band photoelectric detection with high tunability and sensitivity. The Tamm plasmons (TPs) based on the planar metal film/distributed Bragg reflector (DBR) has the advantages of simple structure, low manufacturing cost, and high absorption efficiency. A multilayer thin film device structure for high-performance near-infrared hot electron metal-semiconductor-metal photodetectors is proposed. The structure is based on Ag/Ge2Sb2Te5 (GST) Schottky barrier and TPs formed by SiO2/MoS2 DBR. The simulation results of hot electron emission theory show that DBR can effectively extend the absorption spectrum of Ag film and the response spectrum of the device, and enhance the absorption rate of Ag film and the response of the device. The responsivity which is up to 53 mA/W can be obtained by adjusting the structure parameters of the DBR, the thickness of the Ag film, and the GST layer. At the same time, we also propose a digital display system based on the arrangement of crystalline GST and amorphous GST. It provides a new way for the realization of high-performance near-infrared hot electronic devices and is conducive to expanding the application field of hot electronic photodetectors.

Nanosheets array-induced nanofluidic channels toward efficient primary batteries-coordinated textiles

Flexible hygroelectric generators (HEGs) that derive affordable and sustainable electricity power from omnipresent moisture are promising candidates for smart textile electronics. However, the desired compatibility of high output current and continuous operating voltage is still challenging for wearable HEGs to meet the ever-increasing nanotechnological requirements. Herein, we rationally design and finely synthesize conductive carbonized silk fabrics with in situ growth of SnO/SnO2 nanosheet arrays, which are successfully employed to fabricate high-efficiency wearable HEGs with a maximal power density of 26.66 μW·cm−2 by sandwiching with MXene/cotton fabrics and Al electrodes. Impressively, the vertically interlaced SnO/SnO2 nanosheet arrays supply abundant nanofluidic channels for rapid water diffusive flow with a high flow potential. Combined with the excellent moisture absorption and retention of MXene/cotton textiles, these prepared HEGs process sustained voltage and current outputs of 0.932 V and 0.434 mA over 20,000 s. These flexible HEGs are capable of application in self-powered sensors and micro power supplies, delivering a fresh strategy for the rational design of high-performance and sustainable textile-based electronics.

In situ observation of indium filament growth dynamics in ITO electrode-based memristor

Indium tin oxide (ITO) electrode is commonly used in integrated transparent electronics, including memristor, solar cell, light emitting diode, and photodetector. However, the lack of appropriate understanding of indium (In) ions motion from ITO is the major roadblock to disclose the mechanism of ITO electrode-based memristors. Revealing the filaments growth dynamics is of critical importance to continued devices optimization. Here, we show direct evidence of In filament growth dynamics by in situ transmission electron microscopy, where the In–O bond in ITO would dissociate at high electric field, leading to the In ions transport and cone-like filament formation in the dielectric layer. The In filament formation and melt are responsible for the resistive switching, which can both commence growth toward active ITO and inert Au electrodes, respectively, by controlling the ion mobility. This study can provide a generalized guideline for high performance electronics design and modeling with transparent ITO electrodes.

Recent Advances in Functional Fiber-Based Wearable Triboelectric Nanogenerators.

The quality of human life has improved thanks to the rapid development of wearable electronics. Previously, bulk structures were usually selected for the fabrication of high performance electronics, but these are not suitable for wearable electronics due to mobility limitations and comfortability. Fibrous material-based triboelectric nanogenerators (TENGs) can provide power to wearable electronics due to their advantages such as light weight, flexibility, stretchability, wearability, etc. In this work, various fiber materials, multiple fabrication methods, and fundamentals of TENGs are described. Moreover, recent advances in functional fiber-based wearable TENGs are introduced. Furthermore, the challenges to functional fiber-based TENGs are discussed, and possible solutions are suggested. Finally, the use of TENGs in hybrid devices is introduced for a broader introduction of fiber-based energy harvesting technologies.

Parameters Affecting Interfacial Assembly and Alignment of Nanotubes.

Tangential flow interfacial self-assembly (TaFISA) is a promising scalable technique enabling uniformly aligned carbon nanotubes for high-performance semiconductor electronics. In this process, flow is utilized to induce global alignment in two-dimensional nematic carbon nanotube assemblies trapped at a liquid/liquid interface, and these assemblies are subsequently deposited on target substrates. Here, we present an observational study of experimental parameters that affect the interfacial assembly and subsequent aligned nanotube deposition. We specifically study the water contact angle (WCA) of the substrate, nanotube ink composition, and water subphase and examine their effects on liquid crystal defects, overall and local alignment, and nanotube bunching or crowding. By varying the substrate chemical functionalization, we determine that highly aligned, densely packed, individualized nanotubes deposit only at relatively small WCA between 35 and 65°. At WCA (< 10°), high nanotube bunching or crowding occurs, and the film is nonuniform, while aligned deposition ceases to occur at higher WCA (>65°). We find that the best alignment, with minimal liquid crystal defects, occurs when the polymer-wrapped nanotubes are dispersed in chloroform at a low (0.6:1) wrapper polymer to nanotube ratio. We also demonstrate that modifying the water subphase through the addition of glycerol not only improves overall alignment and reduces liquid crystal defects but also increases local nanotube bunching. These observations provide important guidance for the implementation of TaFISA and its use toward creating technologies based on aligned semiconducting carbon nanotubes.

Synthesis of high-crystalline ReS2 monolayers by sodium-assisted chemical vapor deposition

Featured with highly structural anisotropy, rhenium-based transition metal dichalcogenides (TMDs) and alloys have attracted significant attention in electronics, optoelectronics, energy storage, and catalysis. The controlled growth of large-area, high-quality anisotropic TMDs is critical for associated applications. However, the Jahn–Teller effect and Peierls distortion of the lattice easily induce out-of-plane growth, making it a challenge to prepare uniform-thickness Re-based TMDs. Here, we report a NaCl-assisted chemical vapor deposition strategy for Re-based TMDs and highlight the essential role of Na+ absorption based on a combination of experiments and density functional theory calculations. We found that Cl has little influence on the intermediate products during the reaction process, while Na is responsible for reducing the highest energy barrier required for the formation of Re–Re chains. The barrier for the rate-determining step is reduced by 0.325 eV compared to that without considering Na+ adsorption. Additionally, the field-effect transistor device based on the sodium-assisted synthesized ReS2 monolayer demonstrates superior electrical properties. Our findings not only provide a reliable experimental scheme for the preparation of Re-based semiconductors but also promote the application of ReS2 in high-performance electronics.

Biotemplated precise assembly approach toward ultra-scaled high-performance electronics.

Structural DNA nanotechnology can be programmed into complex designer structures with molecular precision for directing a wide range of inorganic and biological materials. However, the use of DNA-templated approaches for the fabrication and performance requirements of ultra-scaled semiconductor electronics is limited by its assembly disorder and destructive interface composition. In this protocol, using carbon nanotubes (CNTs) as model semiconductors, we provide a stepwise process to build ultra-scaled, high-performance field-effect transistors (FETs) from micron-scale three-dimensional DNA templates. We apply the approach to assemble CNT arrays with uniform pitches scaled between 24.1 and 10.4 nm with yields of more than 95%, which exceeds the resolution limits of conventional lithography. To achieve highly clean CNT interfaces, we detail a rinsing-after-fixing step to remove residual DNA template and salt contaminations present around the contact and the channel regions, without modifying the alignment of the CNT arrays. The DNA-templated CNT FETs display both high on-state current (4-15 μA per CNT) and small subthreshold swing (60-100 mV per decade), which are superior to previous examples of biotemplated electronics and match the performance metrics of high-performance, silicon-based electronics. The scalable assembly of defect-free three-dimensional DNA templates requires 1 week and the CNT arrays can be synthesized within half a day. The interface engineering requires 1-2 d, while the fabrication of high-performance FET and logic gate circuits requires 2-4 d. The structural and performance characterizations of molecular-precise DNA self-assembly and high-performance electronics requires 1-2 d. The protocol is suited for users with expertise in DNA nanotechnology and semiconductor electronics.

Nitrogen Pretreatment of Growth Substrates for Vacancy-Saturated MoS2.

Two-dimensional transition-metal dichalcogenides (2D TMDCs) are considered promising materials for optoelectronics due to their unique optical and electric properties. However, their potential has been limited by the occurrence of atomic vacancies during synthesis. While post-treatment processes have demonstrated the passivation of such vacancies, they increase process complexity and affect the TMDC's quality. We here introduce the concept of pretreatment as a facile and powerful route to solve the problem of vacancies in MoS2. Low-temperature nitridation of the sapphire substrate prior to growth provides a nondestructive method to MoS2 modification without introducing new processing steps or increasing the thermal budget. Spectroscopic characterization and atomic-resolution microscopy reveal the incorporation of nitrogen from the sapphire surface layer into chalcogen vacancies. The resulting MoS2 with nitrogen-saturated defects shows a decrease in midgap states and more intrinsic doping as confirmed by ab initio calculations and optoelectronic measurements. The demonstrated pretreatment method opens up new routes toward future, high-performance 2D electronics, as evidenced by a 3-fold reduction in contact resistance and a 10-fold improved performance of 2D photodetectors.

(Invited) Discussion on Preparation of Single-Walled Carbon Nanotubes for High-Performance Electronics

The unique structure and outstanding properties of single-walled carbon nanotubes (SWCNTs) make them top candidates for future high-performance electronics. Highly pure (>99.9999%) and dense (>125tubes/micron) SWCNTs are desired to present performance surpassing silicon-based devices and chips. Material preparation is the prerequisite of electronic applications. Selective synthesis, purification/sorting, and controlled assembling are procedures that associated with pathways to obtain SWCNT materials for high-performance electronics. However, it’s still not clear that what is the feasible strategy. More discussions and critical thinkings are in urgent need. I will try to review some of the recent developments in the field and discuss the possible directions in future study.