bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fingerprints Indicating Superior Properties of Internal Interfaces in Cu(In,Ga)Se2 Thin‐Film Solar Cells
Authors: Raghuwanshi Mohit , Chugh Manjusha , Sozzi Giovanna , Kanevce Ana , Kühne Thomas D. , Mirhosseini Hossein , Wuerz Roland , Cojocaru‐Mirédin Oana 
Published: July 2022

AbstractGrowth of Cu(In,Ga)Se2 (CIGS) absorbers under Cu‐poor conditions gives rise to incorporation of numerous defects into the bulk, whereas the same absorber grown under Cu‐rich conditions leads to a stoichiometric bulk with minimum defects. This suggests that CIGS absorbers grown under Cu‐rich conditions are more suitable for solar cell applications. However, the CIGS solar cell devices with record efficiencies have all been fabricated under Cu‐poor conditions, despite the expectations. Therefore, in the present work, both Cu‐poor and Cu‐rich CIGS cells are investigated, and the superior properties of the internal interfaces of the Cu‐poor CIGS cells, such as the p–n junction and grain boundaries, which always makes them the record‐efficiency devices, are shown. More precisely, by employing a correlative microscopy approach, the typical fingerprints for superior properties of internal interfaces necessary for maintaining a lower recombination activity in the cell is discovered. These are a Cu‐depleted and Cd‐enriched CIGS absorber surface, near the p–n junction, as well as a negative Cu factor (∆β) and high Na content (>1.5 at%) at the grain boundaries. Thus, this work provides key factors governing the device performance (efficiency), which can be considered in the design of next‐generation solar cells.
Improved Ferroelectricity and Endurance of Hf0.5Zr0.5O2 Thin Films in Low Thermal Budget with Novel Bottom Electrode Doping Technology
Authors: Tian Guoliang , Xu Gaobo , Yin Huaxiang , Yan Gangping , Zhang Zhaohao , Li Lianlian , Sun Xiaoting , Chen Jia , Zhang Yadong , Bi Jinshun , Xiang Jinjuan , Liu Jinbiao , Wu Zhenhua , Luo Jun , Wang Wenwu 
Published: July 2022

AbstractHfO2‐based ferroelectric memory is one of the most attractive candidates for embedded memory in future monolithic‐M3D integrated‐circuit (IC). However, ferroelectricity and endurance will degrade at lower annealing temperatures due to the limitation of the M3D‐IC in thermal budget, which significantly inhibits its potential for many applications. In this work, a novel process technology using As5+ implantation (As‐imp) at the bottom electrode (BE) in TiN/Hf0.5Zr0.5O2(HZO)/TiN capacitors is proposed. The HZO film shows excellent ferroelectricity and improves endurance at the annealing temperatures of 350 and 400 °C, especially when the dose of As‐imp is 1 × 1016, where the endurance of the HZO film is up to 1.5 × 1011, and the remnant polarization (Pr) far exceeds the reference capacitor without BE As‐imp, where 2Pr is greater than 40 °C cm−2 after 1.5 × 1011 cycles. The underlying physical mechanism is that the oxidation reaction of introduced As5+ during the film deposition releases extra oxygen atoms to fill the oxygen vacancies (Vo) near the BE interface due to the occurrence of the thermal reduction reaction in the subsequent annealing process. This study paves the way for the integration of HZO‐based ferroelectric embedded memory in future high‐performance and energy‐efficient 3D‐ICs.
Study of Surfactant‐Induced Deformations at the Interface of Emulsion Droplets by Digital Image Analysis of Droplet Projections
Authors: vom Stein Helena , Volkmer Dirk 
Published: July 2022

AbstractEmulsion droplets do not always have smooth surfaces. Under certain conditions, the formation of surface‐active species at oil–water interfaces leads to interfacial instabilities that cause a spontaneous increase in the droplet surface area, which results in fascinating droplet morphologies. The specific system presented in this study consists of stearic acid encapsulated in an oil droplet and the quaternary ammonium surfactant cetyltrimethylammonium bromide in the aqueous phase. This system is studied by examining the deformation of single emulsion droplets hanging on a capillary tip. By using digital image analysis, the relative perimeters and fractal dimensions from the droplet outlines are calculated and the influences of several process parameters on their temporal development are studied. It is demonstrated that the surfactant concentration, pH value, salt addition, alcohol addition, and viscosity have a considerable impact on the droplet morphology and possible causes for this behavior are discussed. Through this study, important insights are gained into the deformation mechanism and kinetics that can potentially guide the future preparation of particles with special surface morphologies.
Exploration of Physicochemical Mechanism for Negative Bias Temperature Instability in GaN‐HEMTs by Extracting Activation Energy of Dislocations
Authors: Chang Kuan‐Chang , Wang Zhengda , Zhou Qian , Zhang Xinxin , Lin Xinnan , Li Lei 
Published: July 2022

AbstractThe reliability issues caused by negative bias temperature instability (NBTI) impede the rapid expansion of gallium nitride (GaN)‐based high electron mobility transistors (HEMT). Clarifying the physicochemical reactions during the degradation process induced by NBTI is of paramount importance for tracing the origin of NBTI, so as to circumvent the intrinsic reliability problem. However, the investigation of deep‐seated reasons behind NBTI‐related issue still lacks a feasible approach and has not been explored in depth. This paper proposes a conjoint approach that combines electrical measurements, material analysis, and theoretical calculations to comprehensively investigate the molecular basis of degradation presented by NBTI. Extracting the activation energy of dislocations during stress effectively identifies the deep sources of device deterioration. The breaking of NH bonds and migration of hydrogen ions along the dislocations in GaN lattice are primarily responsible for the electrical instabilities according to the theoretical calculation of activation energy, which is also evidenced by material characterizations including transmission electron microscopy, X‐ray photoelectron spectroscopy and Raman analysis. Also, a molecular‐level model that demonstrates the reaction kinetics is well established for the fundamental understanding of the pivotal physicochemical mechanism behind NBTI, thus providing the direction for further optimization of GaN electronics.
Obtaining Ambient‐Stable MXene Ti3C2Tx through Avoidance of Surface Oxidation Active Sites
Authors: Li Xuesong , Xue Ni , Yao Qian , Han Liuyuan , Zhao Xiangyan , Li Bo , He Tao , Tao Xutang 
Published: July 2022

AbstractAs the quintessential representation of MXenes, Ti3C2Tx has attracted widespread scientific interest and has demonstrated unparalleled potential in various applications. However, Ti3C2Tx has always been subject to its ambient instability, which deteriorates the intrinsic properties and limits the practical applications. The mechanism responsible for oxidative degradation of Ti3C2Tx has remained elusive, and the subsequent improvement of the preparation for ambient‐stable Ti3C2Tx is still a challenge. In this paper, the ambient instability of Ti3C2Tx is found to be attributed to the presence of many oxidation active sites on the surface, the formation of which is highly correlated with the enrichment of etching by‐products (AlFx or Al(OF)x). Based on the above findings a slow‐speed etching method is designed, using tetramethylammonium hydroxide as a separate etching‐agent, to avoid adsorption of fluorine‐containing by‐products during etching. The prepared high‐quality Ti3C2Tx flakes exhibit excellent ambient stability even after 4 months of dispersion in water, unlike conventional aqueous Ti3C2Tx dispersions that can only be kept for a few days. The intrinsic stability allows Ti3C2Tx to avoid its decomposition in seawater desalination, and it exhibits superior desalination ability with a maximum reduction of 62.2% in Na+ permeability and a maximum increase of 300% in water flux.
A Breathable and Stretchable Metastructure for a Versatile Hybrid Electronic Skin Patch with Long‐Term Skin Comfort
Authors: Hwang Wonseop , Kim Juhee , Park Seongjin , Kang Tae‐Hyung , Kim Sunho , Lee Kijung , Lee Myoung‐Gyu , Kwak Rhokyun , Choi In‐Suk , Yi Hyunjung 
Published: July 2022

AbstractWith increasingly diverse functionalities of electronic skins (E‐skins), components and structures for the E‐skin have also become more diverse and complex. It is extremely challenging to make all the components and devices required for additional functionalities stretchable and breathable to ensure skin comfort. Herein, we report a facile strategy to realize a versatile hybrid E‐skin patch with great skin comfort by developing a breathable and stretchable metastructure to serve as the platform material of the hybrid E‐skin patch. A Kagome‐based mechanical metastructure made of breathable, stretchable medical adhesive integrates and tethers non‐stretchable or stiff components and devices to the skin, allowing for both the breathability and mechanical comfort of skin. A wireless skin sensor system to sense electrocardiogram (ECG) signals and wirelessly transmit ECG signals in an event‐driven manner such as sending R peaks only is developed on a polyimide‐based flexible printed circuit board. The Kagome metastructure‐tethered wireless ECG sensor patch does not cause significant skin discomfort when worn for five days, and successfully enables the event‐driven wireless monitoring of ECG signals. We envision that this facile and versatile approach expands the type of materials and functionalities of E‐skin for digital healthcare, personalized medicine, and smart prosthetics with emerging functionalities.
Lead‐Free Piezoelectric Composite Based on a Metamaterial for Electromechanical Energy Conversion
Authors: Wang Zehuan , Cheng Jin , Xie Yan , Wang Yunhan , Yu Zhonghui , Li Shuai , Li Liuting , Dong Shuxiang , Wang Hong 
Published: July 2022

AbstractAdditive manufacturing of arbitrary shapes and unique architecture provides remarkable flexibility and simplicity for the preparation of highly complex conformal electronics. This drives up demand for electronic materials with excellent process ability and functionality from one‐step molding of microminiature to large‐scale devices. Herein, a novel method is introduced for fabricating high‐performance barium titanate (BaTiO3)‐polydimethylsiloxane composites based on three‐dimensional (3D)‐printing‐ordered structure of a metamaterial skeleton. When subjected to external mechanical stress, the metamaterial structure facilitates effective stress transfer, resulting in a significantly improved voltage output. In comparison to traditional low‐dimensional ceramic polymer composites, metamaterial‐structured BaTiO3 composites exhibit excellent electromechanical energy conversion properties, thereby enabling tactile imitation applications and mechanical energy harvesting. This study proposes a novel strategy for biological signal identification and implantable self‐powered electronic applications.
Mechanoreceptor Inspired Electronic Skin for Multi‐Modal Tactile Information Decoding
Authors: Gao Yuyu , Zhang Binbin , Liu Yiming , Yao Kuanming , Huang Xingcan , Li Jian , Wong Tsz Hung , Huang Ya , Li Jiyu , Zhou Jingkun , Wu Mengge , Li Hu , Gao Zhan , Park Wooyoung , Yiu Chun Ki , Jia Huiling , Shi Rui , Li Dengfeng , Yu Xinge 
Published: July 2022

AbstractMultimodal force identification by electronic skin (E‐skin) provides comprehensive and precise tactile information that can enhance elaborated functions of fine tactile discrimination, robotic manipulation, and gesture recognition. However, it remains a great challenge to realize such complicated functions from a highly simplified E‐skin sensing system. Here, mimicking the multi‐mechanoreceptor synergistic effect in human skin, a simple, thin, soft, intelligent tactile sensor composed of an asymmetrically arrangement of strain sensing units array for multimodal tactile information decoding is reported. The E‐skin type tactile sensor exhibits good performance with excellent sensitivity for shear force (2.5 N–1), vertical force (0.11 kPa–1), that enables 3D force refactoring, as well as accurate recognition of sliding force for direction tracking. Another unique feature of the E‐skin type tactile sensor is the side force screen effect, that allows the tactile sensor to yield great accuracy and a gauge factor of 1492 in strain measuring. Furthermore, integration of the sensors into E‐skin array offers the capability of capturing dynamic and real‐time stress distribution on the hand in various conditions. This work provides a new route for complex force‐sensing from the simple structure and shows great potential in robotics, human‐machine interface, and virtual reality/augmented reality (VR/AR).
Inverse‐Designed Meta‐Optics with Spectral‐Spatial Engineered Response to Mimic Color Perception
Authors: Munley Chris , Ma Wenchao , Fröch Johannes E. , Tanguy Quentin A. A. , Bayati Elyas , Böhringer Karl F. , Lin Zin , Pestourie Raphaël , Johnson Steven G. , Majumdar Arka 
Published: July 2022

AbstractMeta‐optics have rapidly become a major research field within the optics and photonics community, strongly driven by the seemingly limitless opportunities made possible by controlling optical wavefronts through interaction with arrays of sub‐wavelength scatterers. As more and more modalities are explored, the design strategies to achieve desired functionalities become increasingly demanding, necessitating more advanced design techniques. Herein, the inverse design approach is utilized to create a set of single‐layer meta‐optics that simultaneously focus light and shape the spectra of focused light without using any filters. Thus, both spatial and spectral properties of the meta‐optics are optimized, resulting in spectra that mimic the color matching functions of the CIE 1931 XYZ color space, which links the spectral distribution of a light source to the color perception of a human eye. Experimental demonstrations of these meta‐optics show qualitative agreement with the theoretical predictions and help elucidate the focusing mechanism of these devices.
High‐Performance Inkjet‐Printed Blue QLED Enabled by Crosslinked and Intertwined Hole Transport Layer
Authors: Xie Liming , Yang Jian , Zhao Wenchao , Yi Yuan‐Qiu‐Qiang , Liu Yang , Su Wenming , Li Qing , Lei Wei , Cui Zheng 
Published: July 2022

AbstractA novel crosslinkable 4,4′‐(9,9‐dimethyl‐9H‐fluorene‐2,7‐diyl)bis(N‐phenyl‐N‐(4‐vinylphenyl)aniline) (FLTA‐V) based on TFB repeat unit is designed and synthesized. A blended film with optimized 2:1 weight ratio of TFB and FLTA‐V is employed to act as the effective hole transport layer (HTL) for quantum dot light‐emitting diode (QLED). The resulted HTL is crosslinked and exhibits excellent solvent‐resistant property without any initiators. It also forms a robust network structure and the TFB molecules are intertwined and imprisoned in the network. The HTL then becomes denser, which enhances both intermolecular interactions and π‐π stacking to further promote efficient charge transportation. Moreover, the closeness of highest occupied molecular orbital levels between TFB (−5.4 eV) and FLTA‐V (−5.6 eV) is beneficial for hole injection from HTL to QD layer. The increased surface energy of blended HTL ensures better electrical contact between HTL and QDs, which reduces the leakage current of the device. The combination of these favorable factors has led to the fabricated blue QLED showing a remarkable enhancement of external quantum efficiency (EQE) from 7.23% for the control TFB‐based device to 10.20% for blended HTL‐based device. In addition, a maximum of 6.82% of EQE for inkjet‐printed blue QLED has been achieved, which is the best‐reported high‐efficiency inkjet‐printed blue QLED to date.
Multi‐Wavelength Laser Emission by Hot‐Carriers Transfers in Perovskite‐Graphene‐Chalcogenide Quantum Dots
Authors: Pan Yong , Wang Li , Zhang Yan , Su Xueqiong , Gao Dongwen , Chen Ruixiang , Huang Lun , Sun Wei , Zhao Yuxin , Gao Dangli 
Published: July 2022

AbstractAs a new type of photonic‐chip light source, quantum dot (QD) lasers have recently received remarkable attention. However, two significant problems remain to be solved: the high lasing threshold characteristics and the single wavelength application in a photonic chip. To achieve this, a multi‐wavelength quantum dot laser is proposed. An ultrathin QDs‐film laser with a thickness of 78 nm is developed. The microstructure of MAPbBr3 + graphene + CoGaZnS is studied using Raman spectroscopy and simulation, illustrating the different optical bandgap structures in different combinations. Four‐wavelength lasing at 540, 628, 769, and 824 nm with thresholds of 25 kW cm–2 and 50 kW cm–2 are achieved at room temperature. The finite‐difference time‐domain (FDTD) simulation results suggest a photon‐jumping phenomenon in a fixed period. Subsequently, the transient absorption (TA) spectrum of the QDs‐film is measured to reveal the ultrafast photonics process, which proves the two hot‐carrier transfer processes and the zitterbewegung (ZB) phenomenon in graphene at 416 nm. The ZB‐dominated hot‐carrier transfer from perovskite MAPbBr3 to CoGaZnS is confirmed. This study can contribute to hot‐carrier lasing and light‐source research in photonic chips.
Red‐Emitting Perovskite Variant Cs2PtCl6 Phosphor: Material Design, Luminous Mechanism, and Application in High‐Color‐Rendering White Light‐Emitting Diodes
Authors: Wu Ranyun , Liu Yingmeng , Hu Sanlue , Fu Pengfei , Xiao Zewen 
Published: July 2022

AbstractRecently, A2BX6‐type halide perovskite variant phosphors have been applied for white light‐emitting diodes (LEDs) due to their superior photoluminescence properties, excellent stability, and low‐cost solution‐processability. However, the reported white LEDs, particularly the all‐A2BX6 white LEDs, exhibit insufficient color rendering due to the shortage of red light. In this work, through a rational material design, a red‐emitting perovskite variant Cs2PtCl6 phosphor is developed. The synthesized Cs2PtCl6 powders exhibit a relatively narrow bandgap of 2.91 eV and an intrinsic broadband red emission centered at 670 nm, which is attributed to the triplet self‐trapped excitons associated with the Jahn−Teller‐distorted [PtCl6]2− octahedra in the excited state. Using Cs2PtCl6 as the red phosphor component, an all‐A2BX6 white LED is constructed, achieving a standard white light with a Commission Internationale de l'Eclairage chromaticity coordinate of (0.33, 0.33), a correlated color temperature of 5318 K, and a record high color rendering index of 90. This work represents a significant step toward the application of A2BX6 perovskite variant phosphors for solid‐state lighting.
Phase‐Field Simulations of the Morphology Formation in Evaporating Crystalline Multicomponent Films
Authors: Ronsin Olivier J. J. , Harting Jens 
Published: July 2022

AbstractIn numerous solution‐processed thin films, a complex morphology resulting from liquid–liquid phase separation (LLPS) or from polycrystallization arises during the drying or subsequent processing steps. The morphology has a strong influence on the performance of the final device but unfortunately, the process–structure relationship is often poorly and only qualitatively understood. This is because many different physical mechanisms (miscibility, evaporation, crystallization, diffusion, and advection) are active at potentially different time scales and because the kinetics plays a crucial role: the morphology develops until it is kinetically quenched far from equilibrium. In order to unravel the various possible structure formation pathways, a unified theoretical framework that takes into account all these physical phenomena is proposed. This phase‐field simulation tool is based on the Cahn–Hilliard equations for diffusion and the Allen–Cahn equation for crystallization and evaporation, which are coupled to the equations for the dynamics of the fluid. The behavior of the coupled model based on simple test cases is discussed and verified. Furthermore, how this framework allows to investigate the morphology formation in a drying film undergoing evaporation‐induced LLPS and crystallization, which is typically a situation encountered, is illustrated, for example, in organic photovoltaics applications.
Origami Microwave Imaging Array: Metasurface Tiles on a Shape‐Morphing Surface for Reconfigurable Computational Imaging
Authors: Venkatesh Suresh , Sturm Daniel , Lu Xuyang , Lang Robert J. , Sengupta Kaushik 
Published: July 2022

AbstractOrigami is the art of paper folding that allows a single flat piece of paper to assume different 3D shapes depending on the fold patterns and the sequence of folding. Using the principles of origami along with computation imaging technique the authors demonstrate a versatile shape‐morphing microwave imaging array with reconfigurable field‐of‐view and scene‐adaptive imaging capability. Microwave/millimeter‐wave based array imaging systems are expected to be the workhorse for sensory perception of future autonomous intelligent systems. The imaging capability of a planar array‐based systems operating in complex scattering conditions have limited field‐of‐view and lack the ability to adaptively reconfigure resolution. To overcome this, here, deviations from planarity and isometry are allowed, and a shape‐morphing computational imaging system is demonstrated. Implemented on a reconfigurable Waterbomb origami surface with 22 active metasurface panels that radiate near‐orthogonal modes across 17–27 GHz, capability to image complex 3D objects in full details minimizing the effects of specular reflections in diffraction‐limited sparse imaging with scene adaptability, reconfigurable cross‐range resolution, and field‐of‐view is demonstrated. Such electromagnetic origami surfaces, through simultaneous surface shape‐morphing ability (potentially with shape‐shifting electronic materials) and electromagnetic field programmability, opens up new avenues for intelligent and robust sensing and imaging systems for a wide range of applications.
Hierarchical Design in Nanoporous Metals
Authors: Ying Jie , Lenaerts Silvia , Symes Mark D. , Yang Xiao‐Yu 
Published: July 2022

AbstractHierarchically porous metals possess intriguing high accessibility of matter molecules and unique continuous metallic frameworks, as well as a high level of exposed active atoms. High rates of diffusion and fast energy transfer have been important and challenging goals of hierarchical design and porosity control with nanostructured metals. This review aims to summarize recent important progress toward the development of hierarchically porous metals, with special emphasis on synthetic strategies, hierarchical design in structure–function and corresponding applications. The current challenges and future prospects in this field are also discussed.