Device Performance Research Articles

Enhancing the emissive film quality: a new role of TADF materials for high-performance blue perovskite light-emitting diodes

Thermally activated delayed fluorescence (TADF) materials are widely used in the field of organic light-emitting diodes (OLEDs) because they can capture both singlet and triplet excitons for light emission. However, only scare attention has been paid to the application of TADF materials in perovskite LEDs (PeLEDs) and the understanding of effects of TADF materials in PeLEDs is limited. In this study, a new role of TADF materials for achieving high-quality perovskite films to enhance the performance of PeLEDs is emphasized. TADF materials are introduced into quasi-2D blue PeLEDs to assist in the crystallization of perovskites during film annealing and ensure the formation of high-quality films with reduced defects, enhancing device performance. Additionally, a step-like hole transport layer has been constructed to reduce the hole transport barrier, which can further enhance the performance of PeLEDs. The resultant blue PeLEDs exhibits an external quantum efficiency of 5.44%, which is 12.7-fold higher than that of the control device. Furthermore, a turn-on voltage of 2.6 V is achieved, which is the lowest for TADF-based blue PeLEDs. The findings may not only unlock a new role of TADF materials in blue PeLEDs, but also provide an alternative pathway to achieve high-performance PeLEDs.

Microstructure and characteristics of Zn and Mg-doped LiNbO3 materials for electrochromic devices

In this investigation, polycrystalline targets of lithium niobate (LN), zinc-doped lithium niobate (Zn:LN), and magnesium-doped lithium niobate (Mg:LN) were synthesized utilizing the Hot Isostatic Pressing (HIP) and Cold Isostatic Pressing (CIP) sintering technique. Subsequently, amorphous thin films of LN, Zn:LN, and Mg:LN and electrochromic devices were fabricated via radio frequency (RF) magnetron sputtering. Comprehensive characterization of the microstructure and optoelectronic properties of the targets, films and devices was conducted employing scanning electron microscopy, X-ray diffraction, spectrophotometry, atomic force microscopy, and an electrochemical workstation. Studies have shown that doping with zinc and magnesium enhances the sintering quality of ceramics, reducing lithium vacancies in polycrystalline lithium niobate ceramics. Zinc doping increases the resistance of lithium niobate, whereas magnesium doping introduces a secondary phase that decreases the resistance. The resistances of LN, Zn:LN, and Mg:LN polycrystalline ceramics are 8.35 GΩ, 9.80 GΩ, and 7.61 GΩ, respectively. The doping process refines the growth of the target and film particles, enhancing the microstructural quality. Notably, the ionic conductivity of the Mg:LN film escalates to 1.7 × 10−5 S/cm. Using doped lithium niobate thin films as electrolytes, the electrochromic devices showed a 38 % increase in coloration efficiency and a 46 % improvement in bleaching efficiency, significantly enhancing device performance.

In-situ Raman Observation on Gas Diffusion Electrode/Polyelectrolyte Interface

Polyelectrolytes (PEs) serve as the critical medium for electrochemical reactions in membrane-based electrochemical devices, such as fuel cells and membrane electrolyzers. To optimize membrane-based electrochemical device performance and elucidate reaction mechanisms, there is a pressing need for detailed microscopic molecular information at gas diffusion electrode/PE interfaces. In this work, we designed a novel membrane-based-electrochemical-device-like gas diffusion electrode/polyelectrolyte electrochemical in-situ Raman cell. The cell's configuration and gas transfer characteristics closely mimic those of MBEDs under working conditions. We created a Pt/Nafion(s) interface by hot-pressing satellite Au@SiO2-Pt loaded carbon cloth with a Nafion membrane, and used this interface for electrochemical in-situ surface enhanced Raman spectroscopy (SERS) observation, including oxygen adsorption/desorption processes, structure of interfacial water and functional groups of Nafion under Ar. The cell enables negatively polarize the potential down to -1.6 V vs. RHE without stripping of the solid/solid interface, despite vigorous H2 generation. The stability of the interface under extreme conditions demonstrates rapid gas transfer at the interface. This observation underscores the potential of our in-situ Raman cell for studying various gas-involved reactions under conditions that closely resemble those in operational MBEDs.

A universal resist-assisted metal transfer method for 2D semiconductor contacts

Abstract With the explosive exploration of two-dimensional (2D) semiconductors for device applications, ensuring effective electrical contacts has become critical for optimizing device performance. Here, we demonstrate a universal resist-assisted metal transfer method for creating nearly free-standing metal electrodes on the SiO2/Si substrate, which can be easily transferred onto 2D semiconductors to form van der Waals (vdW) contacts. In this method, polymethyl methacrylate (PMMA) serves both as an electron resist for electrode patterning and as a sacrificial layer. Contacted with our transferred electrodes, MoS₂ exhibits tunable Schottky barrier heights and a transition from n-type dominated to ambipolar conduction with increasing metal work functions, while InSe shows pronounced ambipolarity. Additionally, using α-In2Se3 as an example, we demonstrate that our transferred electrodes enhance resistance switching in ferroelectric memristors. Finally, the universality of our method is evidenced by the successful transfer of various metals with different adhesion forces and complex patterns.

A novel approach for the replacement of accuracy and precision measurements with the visual instrument agreement scale (VIAS) in evaluating the performance of four intraoral scanners and one shade measurement device

ObjectivesThe terms 'accuracy' and 'precision' are tightly defined in color science but are often used ambiguously in dental research. This study introduces the visual instrument agreement scale (VIAS), a new method for determining visual-instrumental agreement in dental colorimetry by comparing visually perceived and measured color differences. Materials and MethodsIn-vivo tooth color measurements were taken from 16 participants using four intraoral scanners (Primescan, Medit i700, Carestream CS3700, Trios 3) and one spectrophotometer (Vita Easyshade V). Visual shade assessment was also performed by one expert observer using the 3D Master shade guide. Statistical significance testing was conducted using the STRESS index to calculate VIAS, and the F-statistic was used to evaluate device performance. ResultsCarestream CS3700 achieved the highest visual-instrumental agreement with a VIAS score of 82%, performing significantly better than the other devices. Primescan, Medit i700, and Trios 3 showed scores of 76%, 75%, and 72%, respectively, with no significant differences between them. Vita Easyshade V scored 57%, performing significantly worse than the other devices. ConclusionsThe overall performance of the intraoral scanners was strong, with Carestream CS3700 approaching excellent performance. The VIAS method offers a practical, color science-based framework for evaluating visual-instrumental agreement and can be easily replicated using the freely available toolbox. Clinical SignificanceIntraoral scanners performed surprisingly better than a spectrophotometer specifically designed for tooth color measurement and which is often regarded as the gold standard. Additionally, VIAS offers a new, scientifically grounded approach for testing visual-instrumental agreement in dental colorimetry.

Comparative Study of Atomic Layer Deposition Supercycle Design Effects on Reliability in Heterogeneous IGZO Channel TFTs

Oxide semiconductor thin-film transistors (TFTs) are promising candidates for application in display backplanes and memory devices. To ensure both high performance and stable electrical properties of oxide TFTs over long-term use, superior mobility and device stability need to be obtained. In this regard, atomic layer deposition (ALD) has gained attention as a facile method for obtaining conformal oxide films under defect-free conditions and adjusting the composition or distribution for targeted TFT performance. Here, we propose that, even with the same bulk composition, variations in the local composition using an ALD supercycle design can significantly affect the TFT performance, particularly the bias-temperature stability. To ascertain the influence of the local cation distribution on the performance, we compared two supercycle designs by reversing the sub-cycles of indium, gallium, and zinc with identical bulk In–Ga–Zn ratios. Despite minimal changes in the electrical characteristics, such as the mobility and threshold voltage, of the two TFTs designed with ALD supercycles, there was a significant difference in their reliability. Devices with an indium-rich IGZO active layer on the back channel exhibited a hump phenomenon and approximately five times greater Vth degradation (ΔVth: -0.67 V to -3.36 V). By conducting an additional case study of IGZO TFTs and film analysis, we confirmed that mobility is largely governed by the bulk composition, whereas the local surface composition, serving as the back channel, is the key to reliability. The device performance results could be confirmed through the surface and bulk analyses of heterogeneous films engineered through the ALD supercycle design. Furthermore, it has been proposed that optimizing the ALD supercycle design is the key to obtaining high-performance oxide semiconductor TFTs.

Toward Ultrathin: Advances in Solution-Processed Organic Semiconductor Transistors.

In recent years, organic semiconductor (OSC) ultrathin films and their solution-processed organic field-effect transistors (OFETs) have garnered attention for their high flexibility, light weight, solution processability, and tunable optoelectronic properties. These features make them promising candidates for next-generation optoelectronic applications. An ultrathin film typically refers to a film thickness of less than 10 nm, i.e., several molecular layers, which poses challenges for OSC materials and solution-processed methods. In this paper, first we introduce the carrier-transport regulation mechanism under ultrathin limits. Second, we summarize various solution-processed techniques for OSC ultrathin films and elucidate advances in their OFETs performance, such as enhanced or maintained mobilities, improved switching ratios, reduced threshold voltages, and minimized contact resistance. The relationship between the ultrathin-film thickness, microstructure of various OSCs (small molecules and polymers), and device performance is discussed. Third, we explore the recent application of OSC ultrathin-film-based OFETs, such as gas sensors, biosensors, photodetectors, and ferroelectric OFETs (Fe-OFETs). Finally, the conclusion is drawn, and the challenges and prospects of ultrathin OSC transistors are presented. Nowadays, research on ultrathin films is still in its early stages; further experience in precise film deposition control is crucial to advancing research and broadening the scope of applications for OSC ultrathin devices.

Design and Investigation of a High-Performance Quartz-Based SAW Temperature Sensor

In this work, a surface acoustic wave (SAW) temperature sensor based on a quartz substrate was designed and investigated. Employing the Coupling-of-Modes (COM) model, a detailed analysis was conducted on the effects of the number of interdigital transducers (IDTs), the number of reflectors, and their spacing on the performance of the SAW device. The impact of the transversal mode of quartz SAWs on the device was subsequently examined using the finite element method (FEM). The simulation results indicate that optimizing these structural parameters significantly enhances the sensor’s sensitivity and frequency stability. SAW devices with optimal structural parameters were fabricated, and their resonant frequencies were tested across a temperature range of 25–150 °C. Experimental results demonstrate that the SAW temperature sensor maintains high performance stability and data reliability throughout the entire temperature range, achieving a Bode-Q of 7700. Furthermore, the sensor exhibits excellent linearity and repeatability. An analysis of the sensor’s response under varying temperature conditions reveals a significant temperature dependency on its Temperature Coefficient of Frequency (TCF). This feature suggests that the sensor possesses potential advantages for applications in industrial process control and environmental monitoring.

High-resolution chemical patterns from negative tone resists for the integration of extreme ultraviolet patterns of metal-oxide resists with directed self-assembly of block copolymers

Extreme ultraviolet (EUV) lithography faces significant challenges in designing suitable resist materials that can provide adequate precision, while maintaining economically viable throughput. These challenges in resist materials have led to printing failures and high roughness in EUV patterns, compromising the performance of semiconductor devices. Integrating directed self-assembly (DSA) of block copolymers (BCPs) with EUV lithography offers a promising solution because, while the BCPs register to the EUV-defined chemical guiding pattern, the thermodynamically determined structures of the BCPs automatically rectify defects and roughness in the EUV pattern. Despite the superior resolution of metal-oxide EUV resists (MORs), their application to DSA is limited by the difficulty in converting them into chemical patterns that allow effective transfer of the rectified patterns of DSA films into inorganic materials. To address this challenge, this study introduces a novel strategy for fabricating chemical patterns using hydrogen silsesquioxane (HSQ), a high-resolution negative tone inorganic resist, as a model system for MORs. Initially, a sacrificial Cr pattern is generated from HSQ patterns via reactive ion etching. The sacrificial Cr pattern is converted into a chemical pattern by first grafting a water-soluble polyethylene oxide brush onto the substrate, then wet etching the Cr, and finally grafting nonpolar polystyrene brushes. Assembling polystyrene-block-poly(methyl methacrylate) on these patterns results in structures oriented and registered with the underlying pattern, achieving 24 nm full-pitch resolutions. This approach has the potential to integrate MOR patterns into the DSA process, thereby enabling the generation of high-quality sub-10 nm patterns with high-χ BCPs.

Nanostructured Thin Films Enhancing the Performance of New Organic Electronic Devices: Does It Make Sense?

Nanostructured Thin Films Enhancing the Performance of New Organic Electronic Devices: Does It Make Sense?

Device Applications Enabled by Bandgap Engineering Through Quantum Dot Tuning: A Review.

Quantum dots (QDs) are becoming essential materials for future scientific and real-world applications, owing to their interesting and distinct optical and electrical properties compared to their bulk-state counterparts. The ability to tune the bandgap of QDs based on size and composition-a key characteristic-opens up new possibilities for enhancing the performance of various optoelectronic devices. These advances could extend to cutting-edge applications such as ultrawide-band or dual-band photodetectors (PDs), optoelectronic logic gates, neuromorphic devices, and security functions. This paper revisits the recent progress in QD-embedded optoelectronic applications, focusing on bandgap tunability. The current limitations and challenges in advancing and realizing QD-based optoelectronic devices are also discussed.

A Review of Advanced Thermal Interface Materials with Oriented Structures for Electronic Devices

In high-power electronic devices, the rapid accumulation of heat presents significant thermal management challenges that necessitate the development of advanced thermal interface materials (TIMs) to ensure the performance and reliability of electronic devices. TIMs are employed to facilitate an effective and stable heat dissipation pathway between heat-generating components and heat sinks. In recent years, anisotropic one-dimensional and two-dimensional materials, including carbon fibers, graphene, and boron nitride, have been introduced as fillers in polymer-based TIMs due to their high thermal conductivity in specific directions. The orientation of the fillers in the polymer matrix has become an important issue in the development of a new generation of high-performance TIMs. To provide a systematic understanding of this field, this paper mainly discusses recent advances in advanced oriented TIMs with high thermal conductivity (>10 W/(m·K)). For each filler, its preparation strategies and enhancement mechanisms are analyzed separately, with a focus on the construction of oriented structures. Notably, there are few reviews related to carbon fiber TIMs, and this paper details recent research results in this field. Finally, the challenges, prospects, and future development directions of advanced TIMs are summarized in the hope of stimulating future research efforts.

Eco-friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles for enhanced dye-sensitized solar cells utilizing oxalis Corniculata leaf extract

An environmentally friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles (NPs) was developed using Oxalis Corniculata leaf (OCL) extract to enhance the performance of dye-sensitized solar cells (DSSCs). The as-synthesized NPs were annealed at 600 °C to improve their crystallinity. X-ray diffraction and field-emission scanning electron microscopy revealed high crystallinity and a sub-100 nm spherical morphology. Annealing reduced the NP size from ∼85 nm to ∼45 nm and decreased the bandgap from 4.97 eV to 4.62 eV, enhancing low-energy photon absorption. Fourier-transform infrared spectroscopy showed changes in the chemical bonding environment, with a higher presence of dangling bonds in the as-prepared NPs compared to the 600 °C-annealed NPs, likely due to the OCL extract. Photoluminescence spectra confirmed strong red emission peaks at 580 nm and 612 nm, with a slight reduction in the full width at half maximum of the electric dipole transition after annealing. Integrating these NPs into TiO₂ matrices in DSSCs improved power conversion efficiency to 8.58%, outperforming both as-prepared NPs (6.88%) and bare TiO₂ cells (5.05%). This green synthesis approach offers a sustainable pathway for slightly enhancing performance of photovoltaic devices, with additional potential for UV-shielding applications when incorporated into PVA films.

Reconfigurable wide-angle broadband terahertz wave antireflection using a non-volatile phase-change material.

Actively wide-angle broadband terahertz (THz) antireflection (AR) coatings with a flexible reconfigurability have a great potential for the development of next-generation versatile THz components and systems with high performance. Here, we present a reconfigurable wide-angle broadband THz AR coating using a phase change material Ge2Sb2Te5 (GST) film, which is based on the impedance matching method. The performance of GST-based AR coating can be effectively achieved by a thermal excitation, exhibiting the complete suppression of unwanted THz-wave reflections for incidence angles from 0∘ to 50∘ in the broad frequency range of 0.1-3.0 THz. Simulation and experimental results show that the GST-based AR coating can efficiently eliminate Fabry-Perot interference caused by unwanted THz-wave reflections from the substrate, thereby significantly improving the performances of THz devices. Moreover, the active AR mechanism of the GST-based coating is investigated, which elucidates the essential role of the phase transition between the amorphous and crystalline phases in changing the conductivity of the film to achieve an impedance matching condition under thermal excitation. Additionally, the non-volatile properties of GST can enable the AR coating to retain a long-term stability for optimal wave-impedance matching without power holding requirements. Our work provides a new, to the best of our knowledge, and promising way for realizing high-performance integrated THz components and systems in the future.

A Synergistically Enhanced Triboelectric-Electromagnetic Hybrid Generator Enabled by Multifunctional Amorphous Alloy for Highly Efficient Self-Powered System.

Triboelectric-electromagnetic hybrid generator (TEHG) has emerged as an effective technology for mechanical energy harvesting. However, the independent operation of triboelectric nanogenerator (TENG) and electromagnetic generator (EMG), along with tribo-materials wear and magnetic field divergence, constrain the device's overall performance. To address these challenges, a synergistically enhanced TEHG (SE-TEHG) is proposed based on the multifunctional amorphous alloy. Following detailed material analyses, Fe72Si8B20 is selected as the synergistic layer for its low surface roughness, high Vickers-hardness, amorphous structure, and high magnetization. Compared to Al, this material not only boosts TENG's output current and current retention rate by 28.75% and 85.24%, but also improves EMG's output power by 51.05%. In constructing a self-powered system with TEHG, a significant impedance discrepancy exists between the energy harvester (with matched impendence of 16 MΩ for TENG and 110 kΩ for EMG) and the application end. Without power management circuits, the demonstrated self-powered variable impedance system achieves an energy utilization efficiency that is 2.98 times greater than the conventional constant impedance system. The integration of multifunctional materials to realize strong-coupling hybrid generators, combined with the customization of variable impedance systems, set a milestone in efficient mechanical energy harvesting and utilization.

Off-label in-silico flow diverter performance assessment in posterior communicating artery aneurysms.

The posterior communicating artery (PComA) is among the most common intracranial aneurysm locations, but flow diverter (FD) treatment with the widely used pipeline embolization device (PED) remains an off-label treatment that is not well understood. PComA aneurysm flow diversion is complicated by the presence of fetal posterior circulation (FPC), which has an estimated prevalence of 4-29% and is more common in people of black (11.5%) than white (4.9%) race. We present the FD-PComA in-silico trial (IST) into FD treatment performance in PComA aneurysms. ISTs use computational modeling and simulation in cohorts of virtual patients to evaluate medical device performance. We modeled FD treatment in 118 virtual patients with 59 distinct PComA aneurysm anatomies, using computational fluid dynamics to assess post-treatment outcome. Boundary conditions were prescribed to model the effects of non-fetal and FPC, allowing for comparison between these subgroups. FD-PComA predicted reduced treatment success in FPC patients, with an average aneurysm space and time-averaged velocity reduction of 67.8% for non-fetal patients and 46.5% for fetal patients (P<0.001). Space and time-averaged wall shear stress on the device surface was 29.2 Pa averaged across fetal patients and 23.5 Pa across non-fetal (P<0.05) patients, suggesting FD endothelialization may be hindered in FPC patients. Morphological variables, such as the size and shape of the aneurysm and PComA size, did not affect the treatment outcome. FD-PComA had significantly lower treatment success rates in PComA aneurysm patients with FPC. We suggest that FPC patients should be treated with an alternative to single PED flow diversion.

Rational Engineering of Phase‐Pure 2D Perovskite Solar Cells

Abstract2D perovskite structures have gained significant attention due to their reliable long‐term stability. Unlike quasi‐2D perovskites, phase‐pure 2D perovskites exhibit a flattened energy landscape and low energy transfer losses, offering substantial benefits for enhancing device efficiency and stability. Recent research on phase‐pure 2D perovskites has shown significant progress, attributed to their unique properties. This review delineates advancements in the study of phase‐pure 2D perovskite materials and elucidates the relationships between crystal structure design, growth, and device performance regulation. Additionally, it summarizes techniques for characterizing phase‐pure 2D structures and methods for their precise synthesis. Finally, an outlook on the future development of phase‐pure 2D perovskites, highlighting the scientific and technological challenges in current research is provided.

Non‐Fused Star‐Shape Giant Trimer Electron Acceptors for Organic Solar Cells with Efficiency over 19 %

AbstractOrganic solar cells (OSCs) based on giant molecular acceptors (GMAs) have attracted extensive attention due to their excellent power conversion efficiency (PCE) and operation stability. However, the large conjugated plane of GMAs poses great challenges in regulating the solubility, over‐size aggregation and yield, which in turn further constrains their development in commercial products. Herein, we employ a non‐fused skeleton strategy to develop novel non‐fused star‐shape trimers (3BTT6F and 3BTT6Cl) for improving device performance. Single‐bond linkage can break the rigid planarity to form a 3D architecture, generating multidimensional charge transfer pathways. Importantly, the non‐fused skeleton strategy can not only significantly improve solubility and synthesis yield, but also effectively suppress molecular excessive aggregation. Consequently, due to the optimized film‐forming process and charge dynamics, 3BTT6F‐based binary device obtains a high PCE of 17.52 %, which is significantly higher than the reported fully fused trimers. Excitingly, 3BTT6F‐based ternary device even obtains a top‐level PCE of 19.26 %. Furthermore, the non‐fused star‐shape configuration also endows these acceptors with enhanced intermolecular interaction in the active layer, demonstrating excellent operational stability. Our work emphasizes the potential of non‐fused star‐shape trimers, providing a new pathway for achieving highly efficient and stable OSCs.

Heterogeneous Nucleation Regulation Amends Unfavorable Crystallization Orientation and Defect Features of Antimony Selenosulfide Film for High‐Efficient Planar Solar Cells

AbstractAntimony selenosulfide (Sb2(S,Se)3) has obtained widespread concern for photovoltaic applications as a light absorber due to superior photoelectric features. Accordingly, various deposition technologies have been developed in recent years, especially hydrothermal deposition method, which has achieved a great success. However, device performances are limited with severe carrier recombination, relating to the quality of absorber and interfaces. Herein, bulk and interface defects are simultaneously suppressed by regulating heterogeneous nucleation kinetics with barium dibromide (BaBr2) introduction. In details, the Br adsorbs and dopes on the polar planes of cadmium sulfide (CdS) buffer layer, promoting the exposure of nonpolar planes of CdS, which facilitates the favorable growth of [hk1]‐Sb2(S,Se)3 films possessing superior crystallinity and small interface defects. Additionally, the Se/S ratio is increased due to the replacement of Se by Br, causing a downshift of the Fermi levels with a benign band alignment and a shallow‐level defect. Moreover, Ba2+ is located at grain boundaries by coordination with S and Se ions, passivating grain boundary defects. Consequently, the efficiency is increased from 7.70 % to 10.12 %. This work opens an avenue towards regulating the heterogeneous nucleation kinetics of Sb2(S,Se)3 film deposited via hydrothermal deposition approach to optimize its crystalline orientation and defect features.

An Optimization of RSRP on Wi-Fi and LTE-LAA Coexistence Networks

Over the last decade, mobile traffic has grown at an exponential rate, resulting in a scarcity and incompetent use of licensed spectrum by mobile network operators. Therefore, it is important to maintain effective communication to avoid disconnecting signals. The technique of regulating the power of a transmitter in order to improve the communication signal or entire quality of service is known as power control. It is mostly used to improve the performance of a communication device by controlling the transmission power. Power control, in most scenarios, allows the transmission or signal power to be scaled, leading to improved signal quality. On the other hand, power control methods are aimed at avoiding unnecessarily high-power transmission. Hence, particle swarm optimization (PSO) is a computational method for optimizing the reference signal received power (RSRP) by iteratively attempting to improve an unnecessarily high-power transmission solution in terms of a given quality measure. The objective of this research is to evaluate the optimum RSRP value and proposed ideal energy detection threshold for Wi-Fi and LTE-LAA in order to obtain fair coexistence between two networks. Thus, simulations for PSO are carried out using MATLAB software. Based on the results obtained, there are improvement in throughput for both networks after PSO implementation therefore, an ideal energy detection threshold is suitable to use in order to get fair coexistence between Wi-Fi and LTE-LAA networks. Consequently, all the results obtained will be used in following research work in order to evaluate user’s handover in various scenarios.