bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tunable Dopants with Intrinsic Counterion Separation Reveal the Effects of Electron Affinity on Dopant Intercalation and Free Carrier Production in Sequentially Doped Conjugated Polymer Films
Authors: Aubry Taylor J. , Winchell K. J. , Salamat Charlene Z. , Basile Victoria M. , Lindemuth Jeffrey R. , Stauber Julia M. , Axtell Jonathan C. , Kubena Rebecca M. , Phan Minh D. , Bird Matthew J. , Spokoyny Alexander M. , Tolbert Sarah H. , Schwartz Benjamin J. 
Published: May 2020

AbstractCarrier mobility in doped conjugated polymers is limited by Coulomb interactions with dopant counterions. This complicates studying the effect of the dopant's oxidation potential on carrier generation because different dopants have different Coulomb interactions with polarons on the polymer backbone. Here, dodecaborane (DDB)‐based dopants are used, which electrostatically shield counterions from carriers and have tunable redox potentials at constant size and shape. DDB dopants produce mobile carriers due to spatial separation of the counterion, and those with greater energetic offsets produce more carriers. Neutron reflectometry indicates that dopant infiltration into conjugated polymer films is redox‐potential‐driven. Remarkably, X‐ray scattering shows that despite their large 2‐nm size, DDBs intercalate into the crystalline polymer lamellae like small molecules, indicating that this is the preferred location for dopants of any size. These findings elucidate why doping conjugated polymers usually produces integer, rather than partial charge transfer: dopant counterions effectively intercalate into the lamellae, far from the polarons on the polymer backbone. Finally, it is shown that the IR spectrum provides a simple way to determine polaron mobility. Overall, higher oxidation potentials lead to higher doping efficiencies, with values reaching 100% for driving forces sufficient to dope poorly crystalline regions of the film.
Toward the Prediction and Control of Glass Transition Temperature for Donor–Acceptor Polymers
Authors: Zhang Song , Alesadi Amirhadi , Selivanova Mariia , Cao Zhiqiang , Qian Zhiyuan , Luo Shaochuan , Galuska Luke , Teh Catherine , Ocheje Michael U. , Mason Gage T. , St. Onge P. Blake J. , Zhou Dongshan , Rondeau‐Gagné Simon , Xia Wenjie , Gu Xiaodan 
Published: May 2020

AbstractSemiconducting donor–acceptor (D–A) polymers have attracted considerable attention toward the application of organic electronic and optoelectronic devices. However, a rational design rule for making semiconducting polymers with desired thermal and mechanical properties is currently lacking, which greatly limits the development of new polymers for advanced applications. Here, polydiketopyrrolopyrrole (PDPP)‐based D–A polymers with varied alkyl side‐chain lengths and backbone moieties are systematically designed, followed by investigating their thermal and thin film mechanical responses. The experimental results show a reduction in both elastic modulus and glass transition temperature (Tg) with increasing side‐chain length, which is further verified through coarse‐grained molecular dynamics simulations. Informed from experimental results, a mass‐per‐flexible bond model is developed to capture such observation through a linear correlation between Tg and polymer chain flexibility. Using this model, a wide range of backbone Tg over 80 °C and elastic modulus over 400 MPa can be predicted for PDPP‐based polymers. This study highlights the important role of side‐chain structure in influencing the thermomechanical performance of conjugated polymers, and provides an effective strategy to design and predict Tg and elastic modulus of future new D–A polymers.
Quasi‐Binary Transition Metal Dichalcogenide Alloys: Thermodynamic Stability Prediction, Scalable Synthesis, and Application
Authors: Hemmat Zahra , Cavin John , Ahmadiparidari Alireza , Ruckel Alexander , Rastegar Sina , Misal Saurabh N. , Majidi Leily , Kumar Khagesh , Wang Shuxi , Guo Jinglong , Dawood Radwa , Lagunas Francisco , Parajuli Prakash , Ngo Anh Tuan , Curtiss Larry A. , Cho Sung Beom , Cabana Jordi , Klie Robert F. , Mishra Rohan , Salehi‐Khojin Amin 
Published: May 2020

AbstractTransition metal dichalcogenide (TMDCs) alloys could have a wide range of physical and chemical properties, ranging from charge density waves to superconductivity and electrochemical activities. While many exciting behaviors of unary TMDCs have been demonstrated, the vast compositional space of TMDC alloys has remained largely unexplored due to the lack of understanding regarding their stability when accommodating different cations or chalcogens in a single‐phase. Here, a theory‐guided synthesis approach is reported to achieve unexplored quasi‐binary TMDC alloys through computationally predicted stability maps. Equilibrium temperature–composition phase diagrams using first‐principles calculations are generated to identify the stability of 25 quasi‐binary TMDC alloys, including some involving non‐isovalent cations and are verified experimentally through the synthesis of a subset of 12 predicted alloys using a scalable chemical vapor transport method. It is demonstrated that the synthesized alloys can be exfoliated into 2D structures, and some of them exhibit: i) outstanding thermal stability tested up to 1230 K, ii) exceptionally high electrochemical activity for the CO2 reduction reaction in a kinetically limited regime with near zero overpotential for CO formation, iii) excellent energy efficiency in a high rate Li–air battery, and iv) high break‐down current density for interconnect applications. This framework can be extended to accelerate the discovery of other TMDC alloys for various applications.
Graded 2D/3D Perovskite Heterostructure for Efficient and Operationally Stable MA‐Free Perovskite Solar Cells
Authors: Yao Qin , Xue Qifan , Li Zhenchao , Zhang Kaicheng , Zhang Teng , Li Ning , Yang Shihe , Brabec Christoph J. , Yip Hin‐Lap , Cao Yong 
Published: May 2020

AbstractAlmost all highly efficient perovskite solar cells (PVSCs) with power conversion efficiencies (PCEs) of greater than 22% currently contain the thermally unstable methylammonium (MA) molecule. MA‐free perovskites are an intrinsically more stable optoelectronic material for use in solar cells but compromise the performance of PVSCs with relatively large energy loss. Here, the open‐circuit voltage (Voc) deficit is circumvented by the incorporation of β‐guanidinopropionic acid (β‐GUA) molecules into an MA‐free bulk perovskite, which facilitates the formation of quasi‐2D structure with face‐on orientation. The 2D/3D hybrid perovskites embed at the grain boundaries of the 3D bulk perovskites and are distributed through half the thickness of the film, which effectively passivates defects and minimizes energy loss of the PVSCs through reduced charge recombination rates and enhanced charge extraction efficiencies. A PCE of 22.2% (certified efficiency of 21.5%) is achieved and the operational stability of the MA‐free PVSCs is improved.
Phase‐Separated, Printed Organic Thin‐Film Transistor‐Based Nonvolatile Memory with Enhanced Data Retention
Authors: Kim Woojo , Kwon Jimin , Lee Yongwoo , Baek Sanghoon , Jung Sungjune 
Published: May 2020

AbstractA nonvolatile memory thin film transistor (TFT) is an essential building block in all electronic applications for calculation and identification. In particular, organic memory TFTs using bilayered polymer electrets have attracted significant attention due to excellent mechanical flexibility and fast operating speed. However, the data retention characteristics over an extended period of time remains a major reliability issue for nonvolatile memory devices. Here, the enhancement of data retention in flexible and printed organic memory TFTs by introducing a phase‐separated tunneling layer is demonstrated. The tunneling layer is formed during an active layer printing process with a blend ink of small‐molecule organic semiconductor and polystyrene insulator. The effect of the dielectric tunneling layer on data retention characteristics is systematically investigated. The printed nonvolatile memory devices with the phase‐separated tunneling layer exhibit significantly improved data retention time of over 10 years, validating the feasibility of applying flexible memory into wearable electronics and smart Internet‐of‐Things devices.
Color‐Tunable Boron‐Based Emitters Exhibiting Aggregation‐Induced Emission and Thermally Activated Delayed Fluorescence for Efficient Solution‐Processable Nondoped Deep‐Blue to Sky‐Blue OLEDs
Authors: Kim Hyung Jong , Godumala Mallesham , Kim Seong Keun , Yoon Jiwon , Kim Chae Yeong , Park Hanun , Kwon Jang Hyuk , Cho Min Ju , Choi Dong Hoon 
Published: May 2020

AbstractThree new color‐tunable (deep‐blue to sky‐blue) and solution‐processable emitters—9′‐(2,12‐di‐tert‐butyl‐5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracen‐7‐yl)‐9′H‐9,3′:6′,9″‐tercarbazole (TB‐3Cz), 9′‐(2,12‐di‐tert‐butyl‐5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracen‐7‐yl)‐9,9″‐diphenyl‐9H,9′H,9″H‐3,3′:6′,3″‐tercarbazole (TB‐P3Cz), and 9‐(2,12‐di‐tert‐butyl‐5,9‐dioxa‐13b‐boranaphtho[3,2,1‐de]anthracen‐7‐yl)‐N3,N3,N6,N6‐tetraphenyl‐9H‐carbazole‐3,6‐diamine (TB‐DACz)—are demonstrated, which are cleverly designed and synthesized by appending a boron‐fused entity as an electron acceptor to different electron‐rich entities containing carbazole derivatives as donors. The thermal, photophysical, electrochemical, and electroluminescent characteristics of all the new materials are extensively investigated. Comprehensive photophysical investigations reveal that these emitters exhibit not only thermally activated delayed fluorescence (TADF) but also aggregation‐induced emission (AIE) properties. Consequently, solution‐processable organic light‐emitting diodes (OLEDs) fabricated using these new materials as nondoped emitters in the emissive layer exhibit a maximum external quantum efficiency (EQE) and Commission Internationale de l'Éclairage (CIE) color coordinates of 9.90% and (0.17, 0.07), respectively, for TB‐3Cz; 6.13% and (0.15, 0.08), respectively, for TB‐P3Cz; and 6.04% and (0.18, 0.40), respectively, for TB‐DACz. As far as it is known, the performance and ultrahigh color purity satisfying the deep‐blue CIE coordinates of the National Television System Committee (NTSC) for TB‐3Cz and TB‐P3Cz are the highest reported thus far for nondoped solution‐processable TADF emitters, indicating the great potential of these materials as deep‐blue luminogens in OLED applications.
Enabling Ultrathin Metamaterial Absorbers with Narrow Slits
Authors: Fu Jichao , Dong Hongguang , He Jinlong , Sun Yuwei , Jin Yi , He Sailing 
Published: May 2020

AbstractMetamaterial absorbers (MAs) consisting of subwavelength units offer flexible design freedom and prominent advantages over traditional absorbers. Here, it is found that narrow slits provide the MAs a significant passageway to control the absorption behavior and obtain an ultrasmall thickness. As narrowing the slits in an MA gradually, two effects appear in turn, of which the former is that the slits help the localized energy leak away from the resonant units to balance the material absorption and radiation leakage rates and sustain perfect absorption, and the latter is that acting as a capacitor, the slits red‐shift the absorption peak. A record ultrathin microwave MA with a thickness of only 1/474 of the working wavelength is demonstrated. Colossal electric field is excited inside ultranarrow slits by the assistance of localized resonance in collecting the incident wave. The finding can be extended to other frequencies, and is fascinating for some areas requiring ultrathin absorption structures or strong interaction between waves and matters.
Rotational Offset Microlens Arrays for Highly Efficient Structured Pattern Projection
Authors: Yang Sung‐Pyo , Kim Jae‐Beom , Seo Yeong‐Hyeon , Jeong Ki‐Hun 
Published: May 2020

AbstractThis article reports the diffractive optical elements of rotational offset microlens arrays for generating highly efficient structured light patterns in active stereoscopic 3D imaging. The double‐side configuration of microlens arrays increases the uniformity of diffraction patterns by using two successive refractions on microlens surfaces. In addition, the rotational offsets between the frontside and the backside microlens arrays with rectangular or hexagonal arrangements control the contrast and the density of structured dot array patterns. Two layers of microlens arrays with high curvature and high fill‐factor are microfabricated on both sides of the glass wafer by using ultrathin fluorocarbon encapsulation, thermal reflow, and parylene gap filling. The rotational offset angles of 22.5°, 28°, and 37° in rectangular and 13.25°, 21.75°, and 27.75° in hexagonal arrangements efficiently provide diffractive dot arrays with high uniformity, contrast, and density by minimizing the overlapping of diffractive patterns. The active stereo imaging using rotational offset microlens arrays successfully acquire high‐resolution depth map for 3D plaster objects with smooth and curved surfaces. The structured light pattern projection using rotational offset microlens arrays will provide promising opportunities for compact advanced imaging systems in industrial, medical, or military applications.
Halogen Substitution in Zero‐Dimensional Mixed Metal Halides toward Photoluminescence Modulation and Enhanced Quantum Yield
Authors: Li Mingze , Li Yawen , Molokeev Maxim S. , Zhao Jing , Na Guangren , Zhang Lijun , Xia Zhiguo 
Published: May 2020

AbstractZero‐dimensional (0D) organic−inorganic hybrid metal halides haveunprecedented degrees of freedom for structural tunability and photoluminescence modulation. Here, the 0D isomorphic hybrid metal mixed halides (C9NH20)9Pb3Zn2Br19(1−x)Cl19x (x = 0–1) with continuous halogen contents control, exhibiting tunable emission and enhancement of photoluminescence quantum yield (PLQY) are reported. The competitive bromine to chlorine substitution process in (C9NH20)9Pb3Zn2Br19(1−x)Cl19x occurs first in [ZnBr4−xClx]2− tetrahedron before the [Pb3Br11−xClx]5− trimer. The increasing Cl content in samples from x = 0 to 1 results in an expected blue shift of emission peak from 565 to 516 nm, and meanwhile a strikingly room temperature PL quantum yield increase from 8% to 91%. Combined experimental characterizations and theoretical calculations indicate that the blue shift of interband transition energy is responsible for the emission peak shift. Moreover, with the increasing Cl content, the enhanced electron−phonon interaction and the weakened thermal‐assisted nonradiative recombination result in more efficient radiative transition channels and ultimately enhanced PLQY. The impact of halogen substitution on electronic structures and optical properties in 0D hybrid metal halides is emphasized in this work as a new strategy to promote the future development of new luminescent materials.
Biluminescence Under Ambient Conditions: Water‐Soluble Organic Emitter in High‐Oxygen‐Barrier Polymer
Authors: Louis Marine , Thomas Heidi , Gmelch Max , Fries Felix , Haft Anna , Lindenthal Jakob , Reineke Sebastian 
Published: May 2020

AbstractBiluminescent organic systems displaying fluorescence and phosphorescence at room temperature under aerated atmosphere still remain uncommon to date. Especially the utilization of the room temperature phosphorescence (RTP) is limited, as it is effectively quenched by oxygen, rendering it incompatible with many applications for use in ambient conditions. So far, only encapsulation to prevent oxygen penetration into the films or the use of special steroid hosts are known concepts to allow conventional biluminescent emitters to show RTP. Here, the design and synthesis of a novel water‐soluble biluminescent emitter is reported. After dispersion in a host matrix, and using host/guest hydrogen‐bonding interactions, easy‐processable highly phosphorescent transparent thin‐films are realized. Their luminescent properties can be activated at will under aerated atmosphere for several weeks without degradation of the system. The polymer (host) mixture can even be readily used for 3D printing, leading to a large range of accessible phosphorescent objects.
High Stability and Temperature‐Dependent Photoluminescence of Orthorhombic CsPbI3 Perovskite Nanoparticles
Authors: Tang Bing , Ruan Lin Ji , Qin Changyun , Shu Ang , He Huimei , Ma Ying 
Published: May 2020

AbstractHigh thermal stability of all‐inorganic perovskite nanocrystals (NCs) offers their potential application in various fields such as solar cells and light‐emitting diodes. However, the cubic cesium lead iodide (α‐CsPbI3) with the most appropriate bandgap for light harvesting is thermodynamically unstable at room temperature and spontaneously transforms into the undesired orthorhombic δ‐CsPbI3. Here, a simple method is demonstrated to synthesize orthorhombic γ‐CsPbI3 NCs using 3‐aminopropyl triethoxysilane molecules as capping ligands. The crystalline structure and morphology of these γ‐CsPbI3 NCs hardly change after exposure to ethanol even though they are capped with fewer ligands. Their high stability is also demonstrated by retaining their photoluminescence (PL) intensity after heating/cooling cycles in the range of 295–375 K, in contrast to a quick destruction of α‐CsPbI3 NCs under the same condition. More importantly, temperature‐dependent PL spectra reveal that the exciton/electron–phonon coupling and exciton recombination process of these γ‐CsPbI3 NCs strongly depend on their particle sizes. This finding may enable versatile design of stable γ‐CsPbI3 NCs with different sizes meeting diverse demands for various applications.
Dielectric Nanoaperture Metasurfaces in Silicon Waveguides for Efficient and Broadband Mode Conversion with an Ultrasmall Footprint
Authors: Yao Chaonan , Wang Yilun , Zhang Jihua , Zhang Xinliang , Zhao Chen , Wang Bin , Singh Subhash C. , Guo Chunlei 
Published: May 2020

AbstractEfficient and reliable mode converters with broadband operation and small footprint will enable high‐density silicon photonic integrated circuits to build high bitrate optical networks and handheld optical devices. Here, all‐dielectric nanoaperture metasurfaces in the silicon layer of a silicon‐on‐insulator platform are reported for mode‐order conversion with an ultrasmall footprint. Utilizing the advantages of an abrupt width change and metasurface, the mode conversion between TE00 and TE10 modes is realized with a conversion efficiency as high as ≈90% in simulations and 83.1% in experiments at λ = 1.55 µm within an ultrashort conversion length of about 2.42 µm, the shortest ever achieved. The incident TE00 mode is converted to TE10 mode with purity of more than 90% in a broadband (Δλ ≈ 230 nm) wavelength range from 1.42 to 1.65 µm. Moreover, optimizing the number, position, and dimension of nanoapertures, it is further demonstrated that the nanoaperture metasurface design can enable mode conversion between silicon waveguides of different thicknesses and different relative positions, and between TM modes.
Integration and reanalysis of transcriptomics and methylomics data derived from blood and testis tissue of men with 47,XXY Klinefelter syndrome indicates the primary involvement of Sertoli cells in the testicular pathogenesis
Authors: Winge Sofia B. , Soraggi Samuele , Schierup Mikkel H. , Rajpert‐De Meyts Ewa , Almstrup Kristian 
Published: May 2020

AbstractKlinefelter syndrome (KS; 47,XXY) is the most common sex chromosomal anomaly and causes a multitude of symptoms. Often the most noticeable symptom is infertility caused by azoospermia with testicular histology showing hyalinization of tubules, germ cells loss, and Leydig cell hyperplasia. The germ cell loss begins early in life leading to partial hyalinization of the testis at puberty, but the mechanistic drivers behind this remain poorly understood. In this systematic review, we summarize the current knowledge on developmental changes in the cellularity of KS gonads supplemented by a comparative analysis of the fetal and adult gonadal transcriptome, and blood transcriptome and methylome of men with KS. We identified a high fraction of upregulated genes that escape X‐chromosome inactivation, thus supporting previous hypotheses that these are the main drivers of the testicular phenotype in KS. Enrichment analysis showed overrepresentation of genes from the X‐ and Y‐chromosome and testicular transcription factors. Furthermore, by re‐evaluation of recent single cell RNA‐sequencing data originating from adult KS testis, we found novel evidence that the Sertoli cell is the most affected cell type. Our results are consistent with disturbed cross‐talk between somatic and germ cells in the KS testis, and with X‐escapee genes acting as mediators.
Mehr als nur ein Netzwerk: Strukturierung retikulärer Materialien im Nano‐, Meso‐ und Volumenbereich
Authors: Haase Frederik , Hirschle Patrick , Freund Ralph , Furukawa Shuhei , Ji Zhe , Wuttke Stefan 
Published: May 2020

AbstractRetikuläre Materialien sind von großem Interesse für Anwendungen in der Katalyse und Stofftrennung sowie der Gasspeicherung und gezielten Wirkstoffzufuhr. Diese offenporigen, ausgedehnten Gerüststrukturen können durch Kristallstrukturdesign auf spezifische Anwendungen zugeschnitten werden. Die Implementierung dieser Materialien in Anwendungsumgebungen erfordert jedoch eine Strukturierung über ihr Kristallgitter hinaus, um die Funktionalität auf molekularer Ebene effektiv mit der makroskopischen Welt zu verbinden. Um diese Barriere zu überwinden, werden als nächster Schritt Strategien für die Strukturierung retikulärer Materialien im Nano‐, Meso‐ und Volumenregime benötigt. In diesem Aufsatz geben wir einen Einblick in die jüngsten Fortschritte für die Herstellung von retikulären Materialien über allen Längenskalen, mit dem Fokus auf Selbstorganisationsstrategien und extern kontrollierten Ansätzen. Wir erwarten, dass bedeutende Forschungsfortschritte bei der Anwendung dieser beiden Ansätze in Verbindung mit retikulären Materialien erreicht werden und diese dabei helfen werden, wichtige Bedürfnisse der Gesellschaft zu bewältigen.
A Stable Integrated Photoelectrochemical Reactor for H2 Production from Water Attains a Solar‐to‐Hydrogen Efficiency of 18 % at 15 Suns and 13 % at 207 Suns
Authors: Khan Mohd A. , Al‐Shankiti Ibraheam , Ziani Ahmed , Wehbe Nimer , Idriss Hicham 
Published: May 2020

AbstractThe major challenge in solar water splitting to H2 and O2 is in making a stable and affordable system for large‐scale applications. We have designed, fabricated, and tested a photoelectrochemical reactor characterized as follows: 1) it comprises an integrated device to reduce the balance of the system cost, 2) it utilizes concentrated sunlight to reduce the photoabsorber cost, and 3) it employs and alkaline electrolyte to reduce catalyst cost and eliminate external thermal management needs. The system consists of an III‐V‐based photovoltaic cell integrated with Ni foil as an O2 evolution catalyst that also protects the cell from corrosion. At low light concentration, without the use of optical lenses, the solar‐to‐hydrogen (STH) efficiency was 18.3 %, while at high light concentration (up to 207 suns) with the use of optical lenses, the STH efficiency was 13 %. Catalytic tests conducted for over 100 hours at 100–200 suns showed no sign of degradation nor deviation from product stoichiometry (H2/O2=2). Further tests projected a system stability of years.