Morphology-Controlled Ion Transport in Mixed-Orientation Polymers.

Advancing iontronics with precisely controlled ion transport is fundamentally important to bridge external organic electronics with the biosystem. This long-standing goal, however, is thus far limited by the trade-off between the active ion electromigration and idle diffusion leakage in the (semi)crystalline film. Here, we presented a mixed-orientation strategy by blending a conjugated polymer, allowing for simultaneously high ion electromigration efficiency and low leakage. Our studies revealed that edge-on aggregation with a significant percolative pathway exhibits much higher ion permeability than that of the face-on counterpart but encounters pronounced leakage diffusion. Through carefully engineering the mixed orientations, the polymer composite demonstrated an ideal switchable ion-transport behavior, achieving a remarkably high electromigration efficiency exceeding one quadrillion ions per milliliter per minute and negligible idle leakage. This proof of concept, validated by drug release in a skin-conformable organic electronic ion pump (OEIP), offers a rational approach for the development of multifunctional iontronic devices.

A Comparatively Low Cost, Easy-To-Fabricate, and Environmentally Friendly PVDF/Garnet Composite Solid Electrolyte for Use in Lithium Metal Cells Paired with Lithium Iron Phosphate and Silicon.

Solid electrolytes may be the answer to overcome many obstacles in developing the next generation of renewable batteries. A novel composite solid electrolyte (CSE) composed of a poly(vinylidene fluoride) (PVDF) base with an active nanofiber filler of aluminum-doped garnet Li ceramic, Li salt lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI), Li fluoride (LiF) stabilizing additive, and plasticizer sulfolane was fabricated. In a Li|CSE|LFP cell with this CSE, a high capacity of 168 mAh g-1 with a retention of 98% after 200 cycles was obtained, representing the best performance to date of a solid electrolyte with a PVDF base and a garnet inorganic filler. In a Li metal cell with Si and Li, it yielded a discharge capacity of 2867 mAh g-1 and was cycled 60 times at a current density of 100 mAh g-1, a significant step forward in utilizing a solid electrolyte of any kind with the desirable Si anode. In producing this CSE, the components and fabrication process were chosen to have a lower cost and improved safety and environmental impact compared with the current state-of-the-art Li-ion battery.

Nanoscale doping of polymeric semiconductors with confined electrochemical ion implantation.

Nanoresolved doping of polymeric semiconductors can overcome scaling limitations to create highly integrated flexible electronics, but remains a fundamental challenge due to isotropic diffusion of the dopants. Here we report a general methodology for achieving nanoscale ion-implantation-like electrochemical doping of polymeric semiconductors. This approach involves confining counterion electromigration within a glassy electrolyte composed of room-temperature ionic liquids and high-glass-transition-temperature insulating polymers. By precisely adjusting the electrolyte glass transition temperature (Tg) and the operating temperature (T), we create a highly localized electric field distribution and achieve anisotropic ion migration that is nearly vertical to the nanotip electrodes. The confined doping produces an excellent resolution of 56 nm with a lateral-extended doping length down to as little as 9.3 nm. We reveal a universal exponential dependence of the doping resolution on the temperature difference (Tg - T) that can be used to depict the doping resolution for almost infinite polymeric semiconductors. Moreover, we demonstrate its implications in a range of polymer electronic devices, including a 200% performance-enhanced organic transistor and a lateral p-n diode with seamless junction widths of <100 nm. Combined with a further demonstration in the scalability of the nanoscale doping, this concept may open up new opportunities for polymer-based nanoelectronics.

N, F-enriched inorganic/organic composite interphases to stabilize lithium metal anodes for long-life anode-free cells.

The practical application of lithium metal batteries is considered to be one of the most promising successors for lithium-ion batteries due to their ability to meet the high-energy storage demands of modern society. However, their application is still hindered by the unstable solid electrolyte interphase (SEI) and uncontrollable dendrite growth. In this study, we propose a robust composite SEI (C-SEI) that consists of a fluorine doped boron nitride (F-BN) inner layer and an organic polyvinyl alcohol (PVA) outer layer. Both theoretical calculations and experimental results demonstrate that the F-BN inner layer induces the formation of favourable components (LiF and Li3N) at the interface, promoting rapid ionic transport and inhibiting electrolyte decomposition. The PVA outer layer acts as a flexible buffer in the C-SEI, ensuring the structural integrity of the inorganic inner layer during lithium plating and stripping. The C-SEI modified lithium anode shows a dendrite-free performance and stable cycle over 1200 h, with an ultralow overpotential (15 mV) at 1 mA cm-2 in this study. This novel approach also enhances the stability of capacity retention rate by 62.3% after 100 cycles even in anode-free full cells (C-SEI@Cu||LFP). Our findings suggest a feasible strategy for addressing the instability inherent in SEI, showing great prospects for the practical application of lithium metal batteries.

Achieving Stable Lithium Metal Anode at 50 mA cm-2 Current Density by LiCl Enriched SEI.

Lithium metal batteries are intensively studied due to the potential to bring up breakthroughs in high energy density devices. However, the inevitable growth of dendrites will cause the rapid failure of battery especially under high current density. Herein, the utilization of tetrachloroethylene (C2 Cl4 ) is reported as the electrolyte additive to induce the formation of the LiCl-rich solid electrolyte interphase (SEI). Because of the lower Li ion diffusion barrier of LiCl, such SEI layer can supply sufficient pathway for rapid Li ion transport, alleviate the concentration polarization at the interface and inhibit the growth of Li dendrites. Meanwhile, the C2 Cl4 can be continuously replenished during the cycle to ensure the stability of the SEI layer. With the aid of C2 Cl4 -based electrolyte, the Li metal electrodes can maintain stable for >300 h under high current density of 50 mA cm-2 with areal capacity of 5 mAh cm-2 , broadening the compatibility of lithium metal anode toward practical application scenarios.

Improving the Performance of Red Organic Light-Emitting Transistors by Utilizing a High-k Organic/Inorganic Bilayer Dielectric.

Integration of electrical switching and light emission in a single unit makes organic light-emitting transistors (OLETs) highly promising multifunctional devices for next-generation active-matrix flat-panel displays and related applications. Here, high-performance red OLETs are fabricated in a multilayer configuration that incorporates a zirconia (ZrOx)/cross-linked poly(vinyl alcohol) (C-PVA) bilayer as a dielectric. The developed organic/inorganic bilayer dielectric renders high dielectric constant as well as improved dielectric/semiconductor interface quality, contributing to enhanced carrier mobility and high current density. In addition, an efficient red phosphorescent organic emitter doped in a bihost system is employed as the emitting layer for an effective exciton formation and light generation. Consequently, our optimized red OLETs displayed a high brightness of 16 470 cd m-2 and a peak external quantum efficiency of 11.9% under a low gate and source-drain voltage of -24 V. To further boost the device performance, an electron-blocking layer is introduced for ameliorated charge-carrier balance and hence suppressed exciton-charge quenching, which resulted in an improved maximum brightness of 20 030 cd m-2. We anticipate that the new device optimization approaches proposed in this work would spur further development of efficient OLETs with high brightness and curtailed efficiency roll-off.

Identifying the Molecular Origins of Green BN-TADF Material Degradation and Device Stability via in†situ Raman Spectroscopy.

There is little investigation into the impact of molecular conformation on device efficiency and degradation of boron-nitrogen thermally activated delayed fluorescence emitters (BN-TADF). Herein, three highly-efficient green BN-TADF emitters have been designed to unveil the impact of peripheral phenyl groups on device efficiencies and lifetimes. Compared to BN-PhOH with the lowest EQEmax of 19 %, BN-PhOCH3 and BN-PhN(CH3 )2 have achieved strongly enhanced EQEmax of 25.6 % and 24.1 %, respectively. Importantly, the device lifetimes (LT50 ) are dramatically improved from 1.7 h of BN-PhOH to 4.4 h of BN-PhOCH3 and 7.7 h of BN-PhN(CH3 )2 without encapsulation. According to in situ Raman spectroscopy and simulations, BN-PhN(CH3 )2 of less conformation change after aging exhibits the best photostability. It is proposed that the torsion angle change between the BN core and the peripheral phenyl group results in BN-TADF degradation. This knowledge means precisely tuning peripheral groups of BN-TADF can achieve both higher device efficiencies and longer lifetimes.

Highly Foldable, Super-Sensitive, and Transparent Nanocellulose/Ceramic/Polymer Cover Windows for Flexible OLED Displays.

Polymer cover windows are important components of flexible OLED displays but they easily generate wrinkles because of their weak folding resistance. Increasing the polymer thickness can improve the folding resistance but it decreases the touch sensitivity. Thus, fabricating highly foldable and supersensitive polymer cover windows is still challenging. Here, by incorporating cellulose nanocrystals (CNCs) and zirconia (ZrO2) into colorless polyimide (CPI), we developed a highly foldable and supersensitive hybrid cover window. Inspired by the theory of elasticity, we added rigid CNCs into CPI to improve the elastic modulus and hence the foldability. ZrO2 was introduced to improve dielectric properties, which leads to improved touch sensitivity. After these modifications, the elastic modulus of the cover windows was increased from 1432 to 2221 MPa, whereas its dielectric constant was increased from 2.95 to 3.46 (@1 × 106 Hz), resulting in significantly enhanced foldability and sensitivity. Meanwhile, because of the nano size of CNCs and ZrO2, the hybrid cover windows exhibit excellent optical properties with the transmittance of ∼88.1%@550 nm and haze of 2.39%. With improved and balanced mechanical, dielectric, and optical properties, these hybrid cover windows overcome current cover windows' defects and could be widely used in next-generation flexible displays.

Narrowband Deep-Blue Multi-Resonance Induced Thermally Activated Delayed Fluorescence: Insights from the Theoretical Molecular Design.

Multi-resonance thermal activated delayed fluorescence (MR-TADF) has been promising with large oscillator strength and narrow full width at half maxima of luminescence, overcoming the compromise of emission intensity and energy criteria of traditional charge transfer TADF frameworks. However, there are still limited theoretical investigations on the excitation mechanism and systematic molecular manipulation of MR-TADF structures. We systematically study the highly localized excitation (LE) characteristics based on typical blue boron-nitrogen (BN) MR-TADF emitters and prove the potential triangular core with theoretical approaches. A design strategy by extending the planar π-conjugate core structure is proposed to enhance the multiple resonance effects. Moreover, several substituted groups are introduced to the designed core, achieving color-tunable functions with relatively small energy split and strong oscillator strength simultaneously. This work provides a theoretical direction for molecular design strategy and a series of potential candidates for highly efficient BN MR-TADF emitters.

Highly Soluble and Stable, High Release Rate Nanocellulose Codrug Delivery System of Curcumin and AuNPs for Dual Chemo-Photothermal Therapy.

As a natural antitumor drug, curcumin (CUR) has received increasing attention from researchers and patients due to its various medicinal properties. However, currently CUR is still restricted due to its low and stand-alone therapeutic effects that seriously limit its clinical application. Here, by using cellulose nanocrystals (CNCs) as a nanocarrier to load CUR and AuNPs simultaneously, we developed a hybrid nanoparticle as a codrug delivery system to enhance the low and stand-alone therapeutic effects of CUR. Aided with the encapsulation of ß-cyclodextrin (ßCD), both the solubility and the stability of CUR are greatly enhanced (solubility increased from 0.89 to 131.7 µg/mL). Owing to the unique rod-like morphology of CNCs, the system exhibits an outstanding loading capacity of 31.4 µg/mg. Under the heat effects of coloaded AuNPs, the system demonstrates a high release rate of 77.63%. Finally, with CNC as a bridge nanocarrier, all aforementioned functions were integrated into one hybrid nanoparticle. The all-in-one integration ensures CUR to have enhanced therapeutic effects and enables the delivery system to exhibit combined chemo-photothermal therapy outcomes. This work presents a significant step toward CUR's clinical application and provides a new strategy for effective and integrative treatment of tumor disease.

Flexible, transparent and tough silver nanowire/nanocellulose electrodes for flexible touch screen panels.

Flexible touch screen panel (f-TSP) has been emerging recently and metallic nanowire transparent conductive electrodes (TCEs) are its key components. However, most metallic nanowire (MNW) TCEs suffer from weak bonding strength between metal nanowire electrode layers and polymer substrates, which causes delamination of TCEs and produces serious declines in durability of f-TSPs. Here, we introduce AgS bonding and develop tough and strong electrode-substrate bonded MNW TCEs, which can enhance durability of f-TSPs significantly. We used silver nanowires (AgNWs) as metal conductive electrode and thiol-modified nanofibrillated cellulose (NFC-HS) nanopaper as substrates. Because of the existence of Ag from AgNWs and S from NFC-HS, strong AgS bonding was generated and tough TCEs were obtained. The TCEs exhibit excellent electrical stability, outstanding optical and electrical properties. The f-TSP devices integrated with the TCEs illustrate striking durability. This technique may provide a promising strategy to produce flexible and tough TCEs for next-generation high-durability f-TSPs.

Disintegrable, transparent and mechanically robust high-performance antimony tin oxide/nanocellulose/polyvinyl alcohol thermal insulation films.

Polymer-based thermal insulation films are widely utilized to reduce the influence of solar radiation. However, current thermal insulation films face several challenges from poor thermal insulation performance and severe environmental pollution, which are caused by the non-disintegratability of polymer substrates. Here, cellulose nanofiber (CNF)/antimony tin oxide (ATO) hybrid films with and without polyvinyl alcohol (PVA) are presented and they can be used as window thermal barrier films and personal thermal management textiles. The hybrid films exhibit prominent thermal insulation performance, blocking 91.07% ultraviolet(UV) light, reflecting 95.19% near-infrared(NIR) light, and transmitting 44.89% visible(VIS) light. Meanwhile, the hybrid films demonstrate high thermal stability, high anti-UV aging stability, and robust mechanical properties. Moreover, the used-up hybrid films based on natural cellulose are of high disintegratability and recyclability. Our present work is anticipated to open up a new avenue for the fabrication of next-generation high-performance thermal insulation films with sustainable and environmentally friendly processes.

Record-Low Subthreshold-Swing Negative-Capacitance 2D Field-Effect Transistors.

Power consumption is one of the most challenging bottlenecks for complementary metal-oxide-semiconductor integration. Negative-capacitance field-effect transistors (NC-FETs) offer a promising platform to break the thermionic limit defined by the Boltzmann tyranny and architect energy-efficient devices. However, it is a great challenge to achieving ultralow-subthreshold-swing (SS) (10 mV dec-1 ) and small-hysteresis NC-FETs simultaneously at room temperature, which has only been reported using the hafnium zirconium oxide system. Here, based on a ferroelectric LiNbO3 thin film with great spontaneous polarization, an ultralow-SS NC-FET with small hysteresis is designed. The LiNbO3 NC-FET platform exhibits a record-low SS of 4.97 mV dec-1 with great repeatability due to the superior capacitance matching characteristic as evidenced by the negative differential resistance phenomenon. By modulating the structure and operating parameters (such as channel length (Lch ), drain-sourse bias (Vds ), and gate bias (Vg )) of devices, an optimized SS from ≈40 to ≈10 mV dec-1 and hysteresis from ≈900 to ≈60 mV are achieved simultaneously. The results provide a new potential method for future highly integrated electronic and optical integrated energy-efficient devices.

Highly Thermally Stable, Green Solvent Disintegrable, and Recyclable Polymer Substrates for Flexible Electronics.

Flexible electronics require its substrate to have adequate thermal stability, but current thermally stable polymer substrates are difficult to be disintegrated and recycled; hence, generate enormous electronic solid waste. Here, a thermally stable and green solvent-disintegrable polymer substrate is developed for flexible electronics to promote their recyclability and reduce solid waste generation. Thanks to the proper design of rigid backbones and rational adjustments of polar and bulky side groups, the polymer substrate exhibits excellent thermal and mechanical properties with thermal decomposition temperature (Td,5% ) of 430 °C, upper operating temperature of over 300 °C, coefficient of thermal expansion of 48 ppm K-1 , tensile strength of 103 MPa, and elastic modulus of 2.49 GPa. Furthermore, the substrate illustrates outstanding optical and dielectric properties with high transmittance of 91% and a low dielectric constant of 2.30. Additionally, it demonstrates remarkable chemical and flame resistance. A proof-of-concept flexible printed circuit device is fabricated with this substrate, which demonstrates outstanding mechanical-electrical stability. Most importantly, the substrate can be quickly disintegrated and recycled with alcohol. With outstanding thermally stable properties, accompanied by excellent recyclability, the substrate is particularly attractive for a wide range of electronics to reduce solid waste generation, and head toward flexible and "green" electronics.

Ultrabroadband Photodetectors up to 10.6 µm Based on 2D Fe3 O4 Nanosheets.

The ultrabroadband spectrum detection from ultraviolet (UV) to long-wavelength infrared (LWIR) is promising for diversified optoelectronic applications of imaging, sensing, and communication. However, the current LWIR-detecting devices suffer from low photoresponsivity, high cost, and cryogenic environment. Herein, a high-performance ultrabroadband photodetector is demonstrated with detecting range from UV to LWIR based on air-stable nonlayered ultrathin Fe3 O4 nanosheets synthesized via a space-confined chemical vapor deposition (CVD) method. Ultrahigh photoresponsivity (R) of 561.2 A W-1 , external quantum efficiency (EQE) of 6.6 × 103 %, and detectivity (D*) of 7.42 × 108 Jones are achieved at the wavelength of 10.6 µm. The multimechanism synergistic effect of photoconductive effect and bolometric effect demonstrates the high sensitivity for light with any light intensities. The outstanding device performance and complementary mixing photoresponse mechanisms open up new potential applications of nonlayered 2D materials for future infrared optoelectronic devices.

Multicolored Cathodically Coloring Electrochromism and Electrofluorochromism in Regioisomeric Star-Shaped Carbazole Dibenzofurans.

In this work, a series of fluorescent cathodically coloring electrochromic (EC) small molecules o-, m-, and p-DBFDCz with 3,5-di(9H-carbazol-9-yl)benzene (DCz) linked to dibenzofuran (DBF) at different substitutional positions were synthesized and fully characterized. These compounds are electroactive and undergo quasi-reversible two-step single-electron reduction generating radical anions and dianions. The absorptions of o-, m-, and p-DBFDCz in the neutral states lie in the UV region (λonset ≈ 350 nm), showing high transparency, while the absorption of their reduced states can be largely tuned across the visible region through driving voltage and substitutional positions. Initially generated spectroelectrochemically radical anions show absorption in the short-wavelength region of ∼380-500 nm with weak broad absorptions at longer wavelengths. On further reduction, these bands disappear on the cost of growing intense bands from dianions at longer wavelengths of 500-700 nm with some tail absorptions in the shorter-wavelength region. This renders the colors of the EC devices based on these materials, which are changed from green to red, yellow to magenta, and light to deep blue for o-, m-, and p-DBFDCz, respectively, covering four legs of the L*a*b* color space. Besides excellent optical contrast (>90%) and high coloration efficiency (up to 504 cm2 C-1), the fluorescence observed in solution of neutral o-, m-, and p-DBFDCz can be modulated between the fluorescence and quenched states by direct electrochemical redox reactions. Both EC and electrofluorochromic (EFC) processes are reversible on cycling. This research demonstrates the feasibility of developing multifunctional EC/EFC materials with multicolored electrochromism through exploiting electrochemical properties of traditional fluorescent small molecules.

Trifluoromethyl Group-Modified Non-Fullerene Acceptor toward Improved Power Conversion Efficiency over 13% in Polymer Solar Cells.

Herein, we report a new molecule structure modification strategy for non-fullerene small-molecule electron acceptors (NFAs) for solar cells through trifluoromethylation of end-capping groups. The synthesized trifluoromethylated acceptor ITCF3 exhibits narrower band gap, stronger light absorption, lower molecular energy levels, and better electron transport property compared to the reference NFA without the trifluoromethyl group (ITIC). Bulk heterojunction solar cells based on ITCF3 combined with the PM6 polymer donor exhibit a significantly improved power conversion efficiency of 13.3% compared with the ITIC-based device (8.4%). This work reveals great potential of trifluoromethylation in the design of efficient photovoltaic acceptor materials.

High-performance near-infrared Schottky-photodetector based graphene/In2S3 van der Waals heterostructures.

Two-dimensional (2D) ß-In2S3 is a natural defective n-type semiconductor attracting considerable interest for its excellent photoelectronic performance. However, ß-In2S3 based photodetectors exhibited a weak near-infrared photoresponse compared to visible wavelength in past reports. In this work, high-quality 2D ß-In2S3 nanosheets were prepared by a space-confined chemical vapor deposition (CVD) method. Graphene/In2S3 van der Waals heterostructures were constructed to realize an enhanced near-infrared photodetection performance by a series of transfer processes. The photodetectors based on graphene/In2S3 van der Waals heterostructures through junction carrier separation exhibited a better infrared performance of high photoresponsivity (R light) of 0.49 mA W-1, external quantum efficiency (EQE) of 0.07%, and detectivity (D*) of 3.05 × 107 jones using an 808 nm laser.

Self-Confined Growth of Ultrathin 2D Nonlayered Wide-Bandgap Semiconductor CuBr Flakes.

2D planar structures of nonlayered wide-bandgap semiconductors enable distinguished electronic properties, desirable short wavelength emission, and facile construction of 2D heterojunction without lattice match. However, the growth of ultrathin 2D nonlayered materials is limited by their strong covalent bonded nature. Herein, the synthesis of ultrathin 2D nonlayered CuBr nanosheets with a thickness of about 0.91 nm and an edge size of 45 µm via a controllable self-confined chemical vapor deposition method is described. The enhanced spin-triplet exciton (Zf , 2.98 eV) luminescence and polarization-enhanced second-harmonic generation based on the 2D CuBr flakes demonstrate the potential of short-wavelength luminescent applications. Solar-blind and self-driven ultraviolet (UV) photodetectors based on the as-synthesized 2D CuBr flakes exhibit a high photoresponsivity of 3.17 A W-1 , an external quantum efficiency of 1126%, and a detectivity (D*) of 1.4 × 1011 Jones, accompanied by a fast rise time of 32 ms and a decay time of 48 ms. The unique nonlayered structure and novel optical properties of the 2D CuBr flakes, together with their controllable growth, make them a highly promising candidate for future applications in short-wavelength light-emitting devices, nonlinear optical devices, and UV photodetectors.

Modulating Electronic Structures of Inorganic Nanomaterials for Efficient Electrocatalytic Water Splitting.

Electrocatalytic water splitting is one of the most promising sustainable energy conversion technologies, but is limited by the sluggish electrochemical reactions. Inorganic nanomaterials have been widely used as efficient catalysts for promoting the electrochemical kinetics. Several approaches to optimize the activities of these nanocatalysts have been developed. The electronic structures of the catalysts play a pivotal role in governing the activity and thus have been identified as an essential descriptor. However, the underlying working mechanisms related to the refined electronic structures remain elusive. To establish the structure-electronic-behavior-activity relationship, a comprehensive overview of the developed strategies to regulate the electronic structures is presented, emphasizing the surface modification, strain, phase transition, and heterostructure. Current challenges to the fundamental understanding of electron behaviors in the nanocatalysts are fully discussed.