Low‐Temperature‐Processed Printed Metal Oxide Transistors Based on Pure Aqueous Inks

Additive patterning of transparent conducting metal oxides at low temperatures is a critical step in realizing low‐cost transparent electronics for display technology and photovoltaics. In this work, inkjet‐printed metal oxide transistors based on pure aqueous chemistries are presented. These inks readily convert to functional thin films at lower processing temperatures (T ≤ 250 °C) relative to organic solvent‐based oxide inks, facilitating the fabrication of high‐performance transistors with both inkjet‐printed transparent electrodes of aluminum‐doped cadmium oxide (ACO) and semiconductor (InO_x ). The intrinsic fluid properties of these water‐based solutions enable the printing of fine features with coffee‐ring free line profiles and smoother line edges than those formed from organic solvent‐based inks. The influence of low‐temperature annealing on the optical, electrical, and crystallographic properties of the ACO electrodes is investigated, as well as the role of aluminum doping in improving these properties. Finally, the all‐aqueous‐printed thin film transistors (TFTs) with inkjet‐patterned semiconductor (InO_x ) and source/drain (ACO) layers are characterized, which show ideal low contact resistance (R _c < 160 Ω cm) and competitive transistor performance (µ _lin up to 19 cm² V^?1 s^?1, Subthreshold Slope (SS) ≤150 mV dec^?1) with only low‐temperature processing (T ≤ 250 °C).     

Adiponitrile (C6H8N2): A New Bi‐Functional Additive for High‐Performance Li‐Metal Batteries

Rechargeable batteries with a Li metal anode and Ni‐rich Li[Ni_xCo_yMn_1?x?y]O₂ cathode (Li/Ni‐rich NCM battery) have been emerging as promising energy storage devices because of their high‐energy density. However, Li/Ni‐rich NCM batteries have been plagued by the issue of the thermodynamic instability of the Li metal anode and aggressive surface chemistry of the Ni‐rich cathode against electrolyte solution. In this study, a bi‐functional additive, adiponitrile (C₆H₈N₂), is proposed which can effectively stabilize both the Li metal anode and Ni‐rich NCM cathode interfaces. In the Li/Ni‐rich NCM battery, the addition of 1 wt% adiponitrile in 0.8 m LiTFSI + 0.2 M LiDFOB + 0.05 M LiPF₆ dissolved in EMC/FEC = 3:1 electrolyte helps to produce a conductive and robust Li anode/electrolyte interface, while strong coordination between Ni⁴⁺ on the delithiated Ni‐rich cathode and nitrile group in adiponitrile reduces parasitic reactions between the electrolyte and Ni‐rich cathode surface. Therefore, upon using 1 wt% adiponitrile, the Li/full concentration gradient Li[Ni_0.73Co_0.10Mn_0.15Al_0.02]O₂ battery achieves an unprecedented cycle retention of 75% over 830 cycles under high‐capacity loading of 1.8 mAh cm^?2 and fast charge–discharge time of 2 h. This work marks an important step in the development of high‐performance Li/Ni‐rich NCM batteries with efficient electrolyte additives.     

Water‐Induced Scandium Oxide Dielectric for Low‐Operating Voltage n‐ and p‐Type Metal‐Oxide Thin‐Film Transistors

Solution‐processed metal‐oxide thin films based on high dielectric constant (k) materials have been extensively studied for use in low‐cost and high‐performance thin‐film transistors (TFTs). Here, scandium oxide (ScO_x) is fabricated as a TFT dielectric with excellent electrical properties using a novel water‐inducement method. The thin films are annealed at various temperatures and characterized by using X‐ray diffraction, atomic‐force microscopy, X‐ray photoelectron spectroscopy, optical spectroscopy, and a series of electrical measurements. The optimized ScO_x thin film exhibits a low‐leakage current density of 0.2 nA cm^?2 at 2 MV cm^?1, a large areal capacitance of 460 nF cm^?2 at 20 Hz and a permittivity of 12.1. To verify the possible applications of ScO_x thin films as the gate dielectric in complementary metal oxide semiconductor (CMOS) electronics, they were integrated in both n‐type InZnO (IZO) and p‐type CuO TFTs for testing. The water‐induced full oxide IZO/ScO_x TFTs exhibit an excellent performance, including a high electron mobility of 27.7 cm² V^?1 s^?1, a large current ratio (I_on/I_off) of 2.7 × 10⁷ and high stability. Moreover, as far as we know it is the first time that solution‐processed p‐type oxide TFTs based on a high‐k dielectric are achieved. The as‐fabricated p‐type CuO/ScO_x TFTs exhibit a large I_on/I_off of around 10⁵ and a hole mobility of 0.8 cm² V^?1 at an operating voltage of 3 V. To the best of our knowledge, these electrical parameters are among the highest performances for solution‐processed p‐type TFTs, which represents a great step towards the achievement of low‐cost, all‐oxide, and low‐power consumption CMOS logics.     

Aqueous Deposition of Ultraviolet Luminescent Columnar Tin‐Doped Indium Hydroxide Films

Indium tin oxide (ITO) has attracted intense interest as the most important transparent conducting oxide (TCO) that sees wide use in many opto‐electronic and photo‐chemical devices. The goal of this study is to explore the possibility of depositing ITO thin films using a bioinspired aqueous deposition route as an alternative. On the surface of sulfonated‐self assembled monolayers, Sn‐doped indium hydroxide films are obtained via a hydrogen peroxide‐assisted method. As a result, the as‐deposited indium tin hydroxide films possess a single hexagonal phase of In(OH)₃· xH₂O (0 ≤ x ≤ 1) with Sn doping percentage of (1.7 ± 0.2) at % and a column‐like hierachical microstructure. Structural, compositional and property studies, including electron microscopy, X‐ray diffraction, photoelectron spectroscopy, optical transmittance, photoluminescence and four‐probe conductivity measurements, are conducted. The possible mechanism based on oriented attachment is discussed for the film growth. Strong room temperature photoluminescence within the near UV range is observed in the case of Sn‐doped, but not in the one of the pure In(OH)₃· xH₂O films. Annealing of the indium tin hydroxide films above 200 °C gives nanocrystalline Sn:In₂O₃ films with higher UV and visible transparency and electrical conductivity compared with those of pure In₂O₃ films. The influence of annealing atmosphere is investigated.     

Fluorinated Polyimide as a Novel High‐Voltage Binder for High‐Capacity Cathode of Lithium‐Ion Batteries

An increase in the energy density of lithium‐ion batteries has long been a competitive advantage for advanced wireless devices and long‐driving electric vehicles. Li‐rich layered oxide, xLi₂MnO₃?(1?x)LiMn_1?y?zNi_yCo_zO₂, is a promising high‐capacity cathode material for high‐energy batteries, whose capacity increases by increasing charge voltage to above 4.6 V versus Li. Li‐rich layered oxide cathode however suffers from a rapid capacity fade during the high‐voltage cycling because of instable cathode–electrolyte interface, and the occurrence of metal dissolution, particle cracking, and structural degradation, particularly, at elevated temperatures. Herein, this study reports the development of fluorinated polyimide as a novel high‐voltage binder, which mitigates the cathode degradation problems through superior binding ability to conventional polyvinylidenefluoride binder and the formation of robust surface structure at the cathode. A full‐cell consisting of fluorinated polyimide binder‐assisted Li‐rich layered oxide cathode and conventional electrolyte without any electrolyte additive exhibits significantly improved capacity retention to 89% at the 100th cycle and discharge capacity to 223–198 mA h g^?1 even under the harsh condition of 55 °C and high charge voltage of 4.7 V, in contrast to a rapid performance fade of the cathode coated with polyvinylidenefluoride binder.     

The Formation of Performance Enhancing Pseudo‐Composites in the Highly Active La1–xCaxFe0.8Ni0.2O3 System for IT‐SOFC Application

The La_1–xCa_xFe_0.8Ni_0.2O_3–δ (0 ≤ x ≤ 0.9) system is investigated for potential application as a cathode material for intermediate temperature solid oxide fuel cells (IT‐SOFCs). A broad range of experimental techniques have been utilized in order to elucidate the characteristics of the entire compositional range. Low A‐site Ca content compositions (x ≤ 0.4) feature a single perovskite solid solution. Compositions with 40% Ca content (x = 0.4) exhibit the highest electrical and ionic conductivities of these single phase materials (250 and 1.9 × 10^?3 S cm^?1 at 800 °C, respectively), a level competitive with state‐of‐the‐art (La,Sr)(Fe,Co)O₃. Between 40 and 50% Ca content (0.4 > x > 0.5) a solubility limit is reached and a secondary, brownmillerite‐type phase appears for all higher Ca content compositions (0.5 ≤ x ≤ 0.9). While typically seen as detrimental to electrochemical performance in cathode materials, this phase brings with it ionic conductivity at operational temperatures. This gives rise to the effective formation of pseudo‐composite materials which feature significantly enhanced performance characteristics, while also providing the closest match in thermal expansion behavior to typical electrolyte materials. This all comes with the advantage of being produced through a simple, single‐step, low‐cost production route without the issues associated with typical composite materials. The highest performing pseudo‐composite material (x = 0.5) exhibits electronic conductivity of 300–350 S cm^?1 in the 600–800 °C temperature range while the best polarisation resistance (R_p) values of approximately 0.2 Ω cm² are found in the 0.5 ≤ x ≤ 0.7 range.     

An Easily Sintered,Chemically Stable,Barium Zirconate‐Based Proton Conductor for High‐Performance Proton‐Conducting Solid Oxide Fuel Cells

Yttrium and indium co‐doped barium zirconate is investigated to develop a chemically stable and sintering active proton conductor for solid oxide fuel cells (SOFCs). BaZr_0.8Y_0.2‐xIn_xO_{3‐ δ} possesses a pure cubic perovskite structure. The sintering activity of BaZr_0.8Y_0.2‐xIn_xO_{3‐ δ} increases significantly with In concentration. BaZr_0.8Y_0.15In_0.05O_{3‐ δ} (BZYI5) exhibits the highest total electrical conductivity among the sintered oxides. BZYI5 also retains high chemical stability against CO₂, vapor, and reduction of H₂. The good sintering activity, high conductivity, and chemical stability of BZYI5 facilitate the fabrication of durable SOFCs based on a highly conductive BZYI5 electrolyte film by cost‐effective ceramic processes. Fully dense BZYI5 electrolyte film is successfully prepared on the anode substrate by a facile drop‐coating technique followed by co‐firing at 1400 °C for 5 h in air. The BZYI5 film exhibits one of the highest conductivity among the BaZrO₃‐based electrolyte films with various sintering aids. BZYI5‐based single cells output very encouraging and by far the highest peak power density for BaZrO₃‐based proton‐conducting SOFCs, reaching as high as 379 mW cm^?2 at 700 °C. The results demonstrate that Y and In co‐doping is an effective strategy for exploring sintering active and chemically stable BaZrO₃‐based proton conductors for high performance proton‐conducting SOFCs.     

Ferroelectric and Magnetic Properties in Room‐Temperature Multiferroic GaxFe2−xO3 Epitaxial Thin Films

GaFeO₃‐type iron oxide is a promising room‐temperature multiferroic material due to its large magnetization. To expand its usability, controlling the ferroelectric and magnetic properties is crucial. In this study, high‐quality Ga_xFe_2–xO₃ (x = 0–1) epitaxial films are fabricated and their properties are systematically investigated. All films exhibit room‐temperature out‐of‐plane ferroelectricity, showing that the coercive electric field (E_c) decreases monotonically with x. Additionally, the films show in‐plane ferrimagnetism with a Curie temperature (T_C) >350 K at x = 0–0.6. The coercive magnetic field (H_c) decreases with x at x ≤ 0.6, but shows a constant value at x > 0.6, whereas the saturated magnetization (M_s) increases with x at x ≤ 0.6, but decreases with x at x > 0.6. X‐ray magnetic circular dichroism reveals that the large magnetization at x = 0.6 is derived from Fe³⁺ (3d⁵) at octahedral sites. The controllable range of the E_c, H_c, and M_s values at room temperature (400–800 kV cm^?1, 1–8 kOe, and 0.2–0.6 µ_B/f.u.) is very wide and differs from those of well‐known multiferroic BiFeO₃. Furthermore, the Ga_xFe_2?xO₃ films exhibit room‐temperature magnetocapacitance effects, indicating that adjusting T_C near room temperature is useful to achieve large room‐temperature magnetocapacitance behavior.     

Block‐Copolymer‐Templated Synthesis of Electroactive RuO2‐Based Mesoporous Thin Films

RuO₂‐based mesoporous thin films of optical quality are synthesized from ruthenium‐peroxo‐based sols using micelle templates made of amphiphilic polystyrene‐polyethylene oxide block copolymers. The mesoporous structure and physical properties of the RuO₂ films (mesoporous volume: 30%; pore diameter: ～30 nm) can be controlled by the careful tuning of both the precursor solution and thermal treatment (150–350 °C). The optimal temperature that allows control of both mesoporosity and nanocristallinity is strongly dependent on the substrate (silicon or fluorine‐doped tin oxide). The structure of the resulting mesoporous films are investigated using X‐ray diffraction, X‐ray photoelectron spectroscopy, and atomic force microscopy. Mesoporous layers are additionally characterized by transmission and scanning electron microscopy and ellipsometry while their electrochemical properties are analyzed via cyclic voltammetry. Thick mesoporous films of ruthenium oxide hydrates, RuO₂ · xH₂O, obtained using a thermal treatment at 280 °C, exhibit capacitances as high as 1000 ± 100 F g^?1 at a scan rate of 10 mV s^?1, indicating their potential application as electrode materials.     

High‐Performance Quantum‐Dot Light‐Emitting Diodes Using NiOx Hole‐Injection Layers with a High and Stable Work Function

Solution‐processed oxide thin films are actively pursued as hole‐injection layers (HILs) in quantum‐dot light‐emitting diodes (QLEDs), aiming to improve operational stability. However, device performance is largely limited by inefficient hole injection at the interfaces of the oxide HILs and high‐ionization‐potential organic hole‐transporting layers. Solution‐processed NiO_x films with a high and stable work function of ≈5.7 eV achieved by a simple and facile surface‐modification strategy are presented. QLEDs based on the surface‐modified NiO_x HILs show driving voltages of 2.1 and 3.3 V to reach 1000 and 10 000 cd m^?2, respectively, both of which are the lowest among all solution‐processed LEDs and vacuum‐deposited OLEDs. The device exhibits a T₉₅ operational lifetime of ≈2500 h at an initial brightness of 1000 cd m^?2, meeting the commercialization requirements for display applications. The results highlight the potential of solution‐processed oxide HILs for achieving efficient‐driven and long‐lifetime QLEDs.     

Extremely low surface recombination velocities on low‐resistivity n‐type and p‐type crystalline silicon using dynamically deposited remote plasma silicon nitride films

Extremely low upper‐limit effective surface recombination velocities (S_eff.max) of 5.6 and 7.4 cm/s, respectively, are obtained on ~1.5 Ω cm n‐type and p‐type silicon wafers, using silicon nitride (SiN_x) films dynamically deposited in an industrial inline plasma‐enhanced chemical vapour deposition (PECVD) reactor. SiN_x films with optimised antireflective properties in air provide an excellent S_eff.max of 9.5 cm/s after high‐temperature (>800 °C) industrial firing. Such low S_eff.max values were previously only attainable for SiN_x films deposited statically in laboratory reactors or after optimised annealing; however, in our case, the SiN_x films were dynamically deposited onto large‐area c‐Si wafers using a fully industrial reactor and provide excellent surface passivation results both in the as‐deposited condition and after industrial‐firing, which is a widely used process in the photovoltaic industry. Contactless corona‐voltage measurements reveal that these SiN_x films contain a relatively high positive charge of (4–8) × 10¹² cm⁻² combined with a relatively low interface defect density of ~5 × 10¹¹ eV⁻¹ cm⁻². Copyright © 2012 John Wiley & Sons, Ltd.     

Nanocasting of Mesoporous In‐TM (TM = Co,Fe, Mn) Oxides: Towards 3D Diluted‐Oxide Magnetic Semiconductor Architectures

Transition metal (Co, Fe, Mn)‐doped In₂O_3?y mesoporous oxides are synthesized by nanocasting using mesoporous silica as hard templates. 3D ordered mesoporous replicas are obtained after silica removal in the case of the In‐Co and In‐Fe oxide powders. During the conversion of metal nitrates into the target mixed oxides, Co, Fe, and Mn ions enter the lattice of the In₂O₃ bixbyite phase via isovalent or heterovalent cation substitution, leading to a reduction in the cell parameter. In turn, non‐negligible amounts of oxygen vacancies are also present, as evidenced from Rietveld refinements of the X‐ray diffraction patterns. In addition to (In_1?xTM_x)₂O_3?y, minor amounts of Co₃O₄, α‐Fe₂O₃, and Mn_xO_y phases are also detected, which originate from the remaining TM cations not forming part of the bixbyite lattice. The resulting TM‐doped In₂O_3?y mesoporous materials show a ferromagnetic response at room temperature, superimposed on a paramagnetic background. Conversely, undoped In₂O_3?y exhibits a mixed diamagnetic‐ferromagnetic behavior with much smaller magnetization. The influence of the oxygen vacancies and the doping elements on the magnetic properties of these materials is discussed. Due to their 3D mesostructural geometrical arrangement and their room‐temperature ferromagnetic behavior, mesoporous oxide‐diluted magnetic semiconductors may become smart materials for the implementation of advanced components in spintronic nanodevices.     

Bimetal–Organic Framework: One‐Step Homogenous Formation and its Derived Mesoporous Ternary Metal Oxide Nanorod for High‐Capacity,High‐Rate,and Long‐Cycle‐Life Lithium Storage

Metal–organic frameworks (MOFs) and relative structures with uniform micro/mesoporous structures have shown important applications in various fields. This paper reports the synthesis of unprecedented mesoporous Ni_xCo_3?xO₄ nanorods with tuned composition from the Co/Ni bimetallic MOF precursor. The Co/Ni‐MOFs are prepared by a one‐step facile microwave‐assisted solvothermal method rather than surface metallic cation exchange on the preformed one‐metal MOF template, therefore displaying very uniform distribution of two species and high structural integrity. The obtained mesoporous Ni_0.3Co_2.7O₄ nanorod delivers a larger‐than‐theoretical reversible capacity of 1410 mAh g^?1 after 200 repetitive cycles at a small current of 100 mA g^?1 with an excellent high‐rate capability for lithium‐ion batteries. Large reversible capacities of 812 and 656 mAh g^?1 can also be retained after 500 cycles at large currents of 2 and 5 A g^?1, respectively. These outstanding electrochemical performances of the ternary metal oxide have been mainly attributed to its interconnected nanoparticle‐integrated mesoporous nanorod structure and the synergistic effect of two active metal oxide components.     

Stamping of Flexible,Coplanar Micro‐Supercapacitors Using MXene Inks

The fast growth of portable smart electronics and internet of things have greatly stimulated the demand for miniaturized energy storage devices. Micro‐supercapacitors (MSCs), which can provide high power density and a long lifetime, are ideal stand‐alone power sources for smart microelectronics. However, relatively few MSCs exhibit both high areal and volumetric capacitance. Here rapid production of flexible MSCs is demonstrated through a scalable, low‐cost stamping strategy. Combining 3D‐printed stamps with arbitrary shapes and 2D titanium carbide or carbonitride inks (Ti₃C₂T_x and Ti₃CNT_x, respectively, known as MXenes), flexible all‐MXene MSCs with controlled architectures are produced. The interdigitated Ti₃C₂T_x MSC exhibits high areal capacitance: 61 mF cm^?2 at 25 µA cm^?2 and 50 mF cm^?2 as the current density increases by 32 fold. The Ti₃C₂T_x MSCs also showcase capacitive charge storage properties, good cycling lifetime, high energy and power densities, etc. The production of such high‐performance Ti₃C₂T_x MSCs can be easily scaled up by designing pad or cylindrical stamps, followed by a cold rolling process. Collectively, the rapid, efficient production of flexible all‐MXene MSCs with state‐of‐the‐art performance opens new exciting opportunities for future applications in wearable and portable electronics.     

Highly Stable Ni‐Based Flexible Transparent Conducting Panels Fabricated by Laser Digital Patterning

A novel simple laser digital patterning process to fabricate Ni‐based flexible transparent conducting panels using solution‐processed nonstoichiometric nickel oxide (NiO_x) thin films and their applications for flexible transparent devices are reported in this study. A large‐scale synthesis route to produce NiO_x nanoparticle (NP) ink is also demonstrated. A low‐power continuous‐wave laser irradiation photothermochemically reduces and sinters selected areas of a NiO_x NP thin film to produce Ni electrode patterns. Owing to the innovative NiO_x NP ink and substantially lowered applied laser power density, Ni conductors can be fabricated, for the first time to the best of the authors' knowledge, even on a polyethylene terephthalate substrate, which is known to have one of the lowest glass‐transition temperatures among polymers. The resultant Ni electrodes exhibit a high‐temperature oxidation resistance up to approximately 400 °C, and high corrosion resistance in tap water and even in seawater. Moreover, a superior mechanical stability of the Ni conductors is confirmed by tape‐pull, ultrasonic‐bath, bending/twisting, and cyclic bending (up to 10 000 cycles) tests. Finally, flexible transparent touch screen panels and electrical heaters are fabricated with mesh‐type Ni conductors to demonstrate possible applications.     

The Locus of Free Charge‐Carrier Generation in Solution‐Cast Zn1–xMgxO/Poly(3‐hexylthiophene) Bilayers for Photovoltaic Applications

The photoconductivity of solution‐cast Zn_1–xMg_xO (x=0‐0.4) and poly(3‐hexylthiophene) (P3HT) thin films, and Zn_1‐xMg_xO/P3HT bilayers is investigated using Time‐Resolved Microwave Conductivity (TRMC) with the aim of determining the locus of free charge carrier generation in the bilayer system. The photoconductivity of Zn_1–xMg_xO thin films, under illumination with 300 nm laser pulses, is limited by the formation of stable excitons and by scattering of the carriers at grain boundaries. The electron mobility in Zn_1–xMg_xO films decreases exponentially with Mg concentration, up to x=0.4. In agreement with previous work, free carriers are observed in the P3HT film under illumination with 500 nm pulses in the absence of an acceptor. Under illumination with 500 nm pulses, where only the polymer absorbs, the TRMC signal for the Zn_1–xMg_xO/P3HT bilayers for x≥0.2 is the same as that of pure P3HT, indicating that free carrier generation in these bilayers occurs predominately by exciton dissociation in the polymer bulk, and not at the interface between the polymer and the solution‐cast oxide. At lower Mg concentrations (x<0.2) the TRMC signal increases with decreasing x following the dependence of the electron mobility in the oxide but its light intensity dependence remains consistent with free carrier generation in the polymer bulk. To explain these results and previously published photovoltaic device data (Adv. Funct. Mater. 2007 , 17, 264) we propose that free carrier generation in the bilayers predominantly occurs in the bulk of P3HT, and is followed by electron injection to the oxide to yield photocurrent in photovoltaic cells. The dependence of the TRMC signal of the bilayers on Mg concentration is explained in terms of the yield for free carrier generation in the polymer and the relative contributions of electrons in the oxide and holes in the polymer.     

Laser‐fired contact optimization in c‐Si solar cells

In this work we study the optimization of laser‐fired contact (LFC) processing parameters, namely laser power and number of pulses, based on the electrical resistance measurement of an aluminum single LFC point. LFC process has been made through four passivation layers that are typically used in c‐Si and mc‐Si solar cell fabrication: thermally grown silicon oxide (SiO₂), deposited phosphorus‐doped amorphous silicon carbide (a‐SiC_x/H(n)), aluminum oxide (Al₂O₃) and silicon nitride (SiN_x/H) films. Values for the LFC resistance normalized by the laser spot area in the range of 0.65–3 mΩ cm² have been obtained. Copyright © 2011 John Wiley & Sons, Ltd.     

Alloy Engineering in Few‐Layer Manganese Phosphorus Trichalcogenides for Surface‐Enhanced Raman Scattering

Manganese phosphorus trichalcogenides are widely used in the field of photocatalysis and magnetic studies due to their broadband gaps. Herein, an alloy engineering method for the few‐layer manganese phosphorus trichalcogenides (MnPS_3–xSe_x, 0 ≤ x ≤ 3) in surface‐enhanced Raman scattering (SERS) is reported. A new strategy, with the coupling of exciton resonance (µ_ex) and photoinduced charge transfer (PICT), is applied to screen out materials for SERS enhancement. According to the calculation of density functional theory, the bandgap of manganese phosphorus trichalcogenides (MnPS₃) can be adjusted to match the band energy of Rhodamine 6G molecules by alloy engineering. Furthermore, a series of few‐layer MnPS_3–xSe_x (0 ≤ x ≤ 3) are fabricated to study the PICT‐induced SERS behavior under resonance excitation. The good performance with a detection limit down to 10^?9 m indicates that the synergistic resonances between µ_ex and PICT are crucial to the enhancement.     

Oxygen‐Deficient Homo‐Interface toward Exciting Boost of Pseudocapacitance

Pseudocapacitors hold great promise as charge storage systems that combine battery‐level energy density and capacitor‐level power density. The utilization of pseudocapacitive material, however, is usually restricted to the surface due to poor electrode kinetics, leading to less accessible charge storage sites and limited capacitance. Here, tin oxide is successfully endowed with outstanding pseudocapacitance and fast electrode kinetics in a negative potential window by engineering oxygen‐deficient homo‐interfaces. The as‐prepared SnO_2?x@SnO_2?x electrode yields a specific capacitance of 376.6 F g^?1 at the current density of 2.5 A g^?1 and retains 327 F g^?1 at a high current density of 80 A g^?1. The theoretical calculation reveals that the oxygen defects are more favorable at homo‐interfaces than at the surface due to the lower defect formation energy. Meanwhile, as compared with the surface, the homo‐interface possesses more stable Li⁺ storage sites that are readily accessed by Li⁺ due to the occurrence of oxygen vacancies, enabling outstanding pseudocapacitance as well as high rate capability. This oxygen‐deficient homo‐interface design opens up new opportunities to develop high‐energy and power pseudocapacitors.     

New Roll‐to‐Roll Processable PEDOT‐Based Polymer with Colorless Bleached State for Flexible Electrochromic Devices

Conjugated electrochromic (EC) polymers for flexible EC devices (ECDs) generally lack a fully colorless bleached state. A strategy to overcome this drawback is the implementation of a new sidechain‐modified poly(3,4‐ethylene dioxythiophene) derivative that can be deposited in thin‐film form in a customized high‐throughput and large‐area roll‐to‐roll polymerization process. The sidechain modification provides enhanced EC properties in terms of visible light transmittance change, Δτ_v = 59% (ΔL* = 54.1), contrast ratio (CR = 15.8), coloration efficiency (η = 530 cm² C^?1), and color neutrality (L* = 83.8, a* = ?4.3, b* = ?4.1) in the bleached state. The intense blue‐colored polymer thin films exhibit high cycle stability (10 000 cycles) and fast response times. The design, synthesis, and polymerization of the modified 3,4‐ethylene dioxythiophene derivative are discussed along with a detailed optical, electrochemical, and spectroelectrochemical characterization of the resulting EC thin films. Finally, a flexible see‐through ECD with a visible light transmittance change of Δτ_v = 47% (ΔL* = 51.9) and a neutral‐colored bleached state is developed.