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Cation-doped cubic Li 7 La 3 Zr 2 O 12 is regarded as a promising solid electrolyte for safe and energy-dense solid-state lithium batteries. However, it suffers from the formation of Li 2 CO 3 and high electronic conductivity, which give rise to an unconformable Li/Li 7 La 3 Zr 2 O 12 interface and lithium dendrites. Herein, composite AlF 3 -Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 solid electrolytes were created based on thermal AlF 3 decomposition and F/O displacement reactions under a high-temperature sintering process. When the AlF 3 is thermally decomposed, it leaves Al 2 O 3 /AlF 3 meliorating the grain boundaries and F - ions partially displacing O 2- ions in the grains. Due to the higher electronegativity of F - in the grains and the grain-boundary modification, these AlF 3 -Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 deliver optimized electronic conduction and chemical stability against the formation of Li 2 CO 3 . The Li/AlF 3 -Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 /Li cell exhibits a low interfacial resistance of ∼16 Ω cm 2 and an ultrastable long-term cycling behavior for 800 h under a current density of 200 μA/cm 2 , leading to Li//LiCoO 2 solid-state batteries with good rate performance and cycling stability.

Herein, we develop a facile wet chemical method for the synthesis of Ag 2 Te powders at room temperature and flexible Ag 2 Te/nylon thermoelectric (TE) films are prepared by vacuum-assisted filtration of the synthesized Ag 2 Te powders and then hot pressing. Because of the good crystallinity of Ag 2 Te grains and continuous grain boundaries, an optimized film exhibits a power factor of 513 μW m -1 K -2 at 300 K, which stands among the highest values reported for Ag 2 Te-based films to date. In addition, the film also has good flexibility. A four-leg flexible TE device assembled with the film generates a power density of 5.46 W m -2 at a temperature gradient of 31.8 K. This work provides a facile and environmentally friendly method for preparing flexible Ag 2 Te films.

Recent studies have shown that silver selenide is a promising thermoelectric material at room temperature. Herein, flexible films with a nominal composition of (Ag 1- x Cu x ) 2 Se are prepared by a simple and efficient one-pot method combined with vacuum-assisted filtration and hot pressing. The thermoelectric properties of the films are regulated by both cationic doping and a dual-phase strategy via a wet chemical method. As the x increases, not only Cu is doped into the Ag 2 Se, but different new phases (CuAgSe and/or CuSe 2 ) also appear. The (Ag 1- x Cu x ) 2 Se film with x = 0.02 composed of Cu-doped Ag 2 Se and CuAgSe shows a high PF of ∼2540 μW m -1 K -2 ( ZT ∼ 0.90) and outstanding flexibility at room temperature. The high thermoelectric properties of the film are due to the effect of Cu doping and the CuAgSe phase, including the increase in electrical conductivity caused by doping, the enhanced phonon scattering at the Ag 2 Se/CuAgSe interface, and the interaction between the energy filtering effect and the doping effect. In addition to the high output performance (PD max = 28.08 W m -2 , Δ T = 32.2 K), the flexible device assembled with the (Ag 0.98 Cu 0.02 ) 2 Se film also has potential applications as a temperature sensor.

Herein, a flexible Ag 2 Se/Se composite film with a high power factor has been fabricated on a nylon membrane. The film has a high density and contains well-crystallized Ag 2 Se grains and embedded Se nanoinclusions, which exhibits not only excellent flexibility but also a comparably large room-temperature power factor and Seebeck coefficient of up to 2023 μW m -1 K -2 and -155 μV K -1 , respectively. The high Seebeck coefficient is ascribed to the energy-filtering effect as caused by the Se/Ag 2 Se heterointerface. The assembled flexible thermoelectric generator (4-leg) exhibits a maximum output power of 1135 nW and a power density of up to 16.4 W m -2 when the applied temperature difference is 30 K. This work offers a feasible method to design high-performance and low-cost flexible thermoelectric generators used for wearable electronics.

Flexible thermoelectric (TE) generators have recently attracted increasing attention as they have the potential to power wearable devices using the temperature difference between the human body and the environment. Ag 2 S is recently reported to have plasticity near room temperature; however, it has very low electrical conductivity, leading to its poor TE property. Here, to improve the TE property, different amounts of Se (Se/Ag 2 S molar ratios being 0.4, 0.5, and 0.6) solid solution-substituted Ag 2 S films on a nylon membrane are prepared by combing wet-chemical synthesis, vacuum filtration, and hot-pressing. The film (Se/Ag 2 S molar ratio = 0.6) exhibits a better TE performance with a power factor of 477.4 ± 15.20 μW m -1 K -2 at room temperature, which is comparable to that of bulk Ag 2 S 1- x Se x . In addition, the film possesses excellent flexibility (only ∼5.4% decrease in electrical conductivity after 2000 times bending along a rod with a radius of 4 mm). The power density of a 6-leg TE generator assembled with the film is 6.6 W/m 2 under a temperature difference of 28.8 K. This work provides a facile new route to Ag 2 S-based TE films with low cost, high TE performance, and ultrahigh flexibility.

MXene-based microsupercapacitors (MSCs) have promoted the development of on-chip energy storage for miniaturized and portable electronics due to the small size, high power density and integration density. However, restricted energy density and operating voltage invariably create obstacles to the practical application of MSCs. Here, we report a symmetric MXene-based on-chip MSC, achieving an ultrahigh energy density of 75 mWh cm -3 with high operating voltage of 1.2 V, which are almost the highest values among all reported symmetric MXene MSCs. The adjustment strategy of acetone on the viscosity and surface tension of MXene ink, along with the natural sedimentation strategy, can effectively prevent the orderly stacking of MXene sheets. Further, we developed an all-in-one Si-electronics with three series MSCs through laser-etching technology, obviously presenting high integration capacity and processing compatibility. Thus, this work will contribute to the development of high integration all-in-one electronics with high energy density MXene-based MSCs.

In this work, we developed a facile method to fabricate low-cost, flexible, and high-thermoelectric-performance n-type Ag 2 Se 1- x S x @(Ag 2 S 1- y Se y /S) composite film on a nylon membrane. The composite film was prepared by first performing wet-chemical synthesis of the S-doped Ag 2 Se powder, then vacuum-assisted filtration of the powder on a nylon membrane, and finally hot-pressing. Transmission electron microscopy (TEM) observation and energy-dispersive system (EDS) analysis of the film revealed that the film had a porous network-like microstructure, in which Ag 2 Se 1- x S x sub-micron grains formed the skeleton and are coated by a ∼15 nm thick layer of S-rich Ag 2 S 1- y Se y nanograins mixed with an S amorphous phase. The film showed a power factor of ∼954.7 μW·m -1 ·K -2 at 300 K and superior flexibility (94.4% of the original electrical conductivity was preserved after bending 2000 times around a rod with a radius of 4 mm). Moreover, a six-leg flexible thermoelectric generator was assembled with the film and produced a maximum power of 6.67 μW (corresponding power density ∼14.8 W/m 2 ) at a temperature difference of 38.7 K. This work reveals a novel approach to explore high-performance and low-cost flexible thermoelectric devices suitable for room-temperature applications.

Herein, we fabricated an Ag/Ag 2 Se composite film on a flexible nylon membrane with a high power factor and excellent flexibility. First, Ag nanoparticles and multiscale Ag 2 Se nanostructure composite powders were prepared by wet chemical synthesis using Se nanowires, silver nitrate, and l-ascorbic acid as raw materials, followed by vacuum-assisted filtration of the composite powders on a porous nylon membrane and then hot pressing. The optimized composite film shows a very high power factor of 1860.6 μW m -1 K -2 (with a corresponding electrical conductivity of 3958 S cm -1 ) at room temperature. The composite film retains 93.3% of the original electrical conductivity after 1000 bending cycles around a rod with a diameter of 8 mm. At a temperature difference of 27 K, an 8-leg thermoelectric prototype device assembled with the optimized composite film generates a maximum power of 7.14 μW with a corresponding power density of 8.74 W m -2 . This work provides a new strategy to synthesize flexible thermoelectric films with both a high power factor and high electrical conductivity.

Rich chemistry and surface functionalization provide MXenes enhanced electrochemical activity yet severely exacerbate their self-discharge behavior in supercapacitors. However, this self-discharge behavior and its related mechanism are still remaining issues. Herein, we propose a chemically interface-tailored regulation strategy to successfully unravel and efficiently alleviate the self-discharge behavior of Ti 3 C 2 T x MXene-based supercapacitors. As a result, Ti 3 C 2 T x MXenes with fewer F elements (∼0.65 atom %) show a positive self-discharge rate decline of ∼20% in comparison with MXenes with higher F elements (∼8.09 atom %). Such decline of the F elements can highly increase tight-bonding ions corresponding to an individual self-discharge process, naturally resulting in a dramatic 50% increase of the transition potential ( V T ). Therefore, the mixed self-discharge rate from both tight-bonding (contain fewer F elements) and loose-bonding ions (contain more F elements) is accordingly lowered. Through chemically interface-tailored engineering, the significantly changed average oxidation state and local coordination information on MXene affected the interaction of ion counterparts, which was evidently revealed by X-ray absorption fine structures. Theoretically, this greatly improved self-discharge performance was proven to be from higher adsorption energy between the interface of the electrode and the electrolyte by density functional theory. Therefore, this chemically interface-tailored regulation strategy can guide the design of high-performance MXene-based supercapacitors with low self-discharge behavior and will promote its wider commercial applications.

Solid-state composite polymer electrolytes (CPEs) usually suffer from intrinsic low ionic conductivity and a solid-solid interface, badly inhibiting their widespread commercial application in all-solid-state Li-metal battery (ASSLMB) energy storage. Herein, a synergetic strategy using strong Lewis acid-base and weak hydrogen bonds was employed for self-assembly in situ construction of three-dimensional (3D) network-structured poly(ethylene oxide) (PEO) and SiO 2 CPEs (PEO@SiO 2 ). Ascribed to this synergistically rigid-flexible coupling dynamic strategy, a harmonious incorporation of monodispersed SiO 2 nanoparticles into PEO could remarkably reduce crystallinity of PEO, significantly enhancing the ionic conductivity (∼1.1 × 10 -4 S cm -1 at 30 °C) and dramatically facilitating solid electrolyte interface stabilization (electrochemical stability window > 4.8 V at 90 °C). Moreover, the PEO@SiO 2 -based ASSLMBs possess excellent rate capability over a wide temperature range (∼105 mA h g -1 under 2 C at 90 °C), high temperature cycling capacity (retaining 90 mA h g -1 after 100 cycles at 90 °C), and high specific capacity (146 mA h g -1 under 0.3 C at 90 °C). Unambiguously, these high ionic conductivity CPEs along with excellent flexibility and safety can be one of the most promising candidates for high-performance ASSLMBs, evidently revealing that this synergistically rigid-flexible coupling dynamic strategy will open up a way to exploit the novel high ionic conductivity solid-state electrolytes.

Metal-semiconductor contact has been a critical topic in the semiconductor industry because it influences device performance remarkably. Conventional metals have served as the major contact material in electronic and optoelectronic devices, but such a selection becomes increasingly inadequate for emerging novel materials such as two-dimensional (2D) materials. Deposited metals on semiconducting 2D channels usually form large resistance contacts due to the high Schottky barrier. A few approaches have been reported to reduce the contact resistance but they are not suitable for large-scale application or they cannot create a clean and sharp interface. In this study, a chemical vapor deposition (CVD) technique is introduced to produce large-area semiconducting 2D material (2H MoTe 2 ) planarly contacted by its metallic phase (1T' MoTe 2 ). We demonstrate the phase-controllable synthesis and systematic characterization of large-area MoTe 2 films, including pure 2H phase or 1T' phase, and 2H/1T' in-plane heterostructure. Theoretical simulation shows a lower Schottky barrier in 2H/1T' junction than in Ti/2H contact, which is confirmed by electrical measurement. This one-step CVD method to synthesize large-area, seamless-bonding 2D lateral metal-semiconductor junction can improve the performance of 2D electronic and optoelectronic devices, paving the way for large-scale 2D integrated circuits.

Sensing devices with wearability would open the door to many advanced applications including soft robotics, artificial intelligence, and healthcare monitoring. Here, inspired by the configuration of the human epidermis, we present a flexible three-dimensional (3D) cellular sensor array (CSA) via a one-step thermally induced phase separation method. The CSA was framed by the 3D cellular electret with caged piezoelectric nanoparticles, which was ultrathin (80 μm), lightweight, and highly robust. For biomedical sensing, the 3D-CSA holds a decent pressure sensitivity up to 0.19 V kPa -1 with a response time of less than 16 ms. Owing to its rigid structural symmetry, the 3D-CSA could be identically operated from its both sides. It was demonstrated to successfully measure the human heartbeat, detect the eyeball motion for sleeping monitoring, and tactile imaging. Mimicking the functionalities of the human skin with a self-powered operation feature, the 3D-CSA was expected to represent a substantial advancement in wearable electronics for healthcare.

The application of exciplex energy has become a unique way to achieve organic light-emitting diodes (OLEDs) with high efficiencies, low turn-on voltage, and low roll-off. Novel δ-carboline derivatives with high triplet energy (T 1 ≈ 2.92 eV) and high glass transition temperature (T g ≈ 153 °C) were employed to manipulate exciplex emissions in this paper. Deep blue (peak at 436 nm) and pure blue (peak at 468 nm) thermally activated delayed fluorescence (TADF) of exciplex OLEDs were demonstrated by utilizing them as emitters with the maximum current efficiency (CE) of 4.64 cd A -1 , power efficiency (PE) of 2.91 lm W -1 , and external quantum efficiency (EQE) of 2.36%. Highly efficient blue phosphorescent OLEDs doped with FIrpic showed a maximum CE of 55.6 cd A -1 , PE of 52.9 lm W -1 , and EQE of 24.6% respectively with very low turn on voltage at 2.7 V. The devices still remain high CE of 46.5 cd A -1 at 100 cd m -2 , 45.4 cd A -1 at 1000 cd m -2 and 42.3 cd A -1 at 5000 cd m -2 with EQE close to 20% indicating low roll-off. Manipulating blue exciplex emissions by chemical structure gives an ideal strategy to fully utilize all exciton energies for lighting of OLEDs.

The performance of small molecular organic photovoltaic materials is typically limited by their low exciton diffusion lengths, poor solubility, and poor energy level alignment with fullerenes so that the design and synthesis of new materials remain a top priority. To overcome these limitations, we explored the use of an iridium complex as a donor material with the potential for compatibility with solution processing, long exciton diffusion length and easy molecular modification for tunable optical or electrical properties. A bilayer device with a cyclometalated iridium complex and C60 resulted in a power conversion efficiency as high as 2.8%. Furthermore, a VOC of 1 V was achieved in the bilayer device despite an estimated exciton energy of only 1.55 eV, and the device showed minimal temperature and light intensity dependence.

In order to investigate the ground state and excited state properties of Pt(N(∧)C(∧)N)X, we have prepared a series of Pt complexes, where N(∧)C(∧)N aromatic chelates are derivatives of m-di(2-pyridinyl)benzene (dpb) and X are monoanionic and monodentate ancillary ligands including halide and phenoxide. Facile synthesis of platinum m-di(2-pyridinyl)benzene chloride and its derivatives, using controlled microwave heating, was reported. This method not only shortened the reaction time but also improved the reaction yield for most of the Pt complexes. Two Pt(N(∧)C(∧)N)X complexes have been structurally characterized by X-ray crystallography. The change of functional group does not affect the structure of the core Pt(N(∧)C(∧)N)Cl fragment. Both molecules pack as head-to-tail dimers, each molecule of the dimer related to the other by a center of inversion. The electrochemical studies of all Pt complexes demonstrate that the oxidation process occurs on the metal-phenyl fragment and the reduction process is associated with the electron accepting groups like pyridinyl groups and their derivatives. The maximum emission wavelength of the Pt(N(∧)C(∧)N)X complexes ranges between 471 and 610 nm, crossing the spectrum of visible light. Most of the Pt complexes are strongly luminescent (Φ = 0.32-0.63) and have short luminescence lifetimes (τ = 4-7 μs) at room temperature. The lowest excited state of the Pt(N(∧)C(∧)N)X complexes is identified as a dominant ligand-centered (3)π-π* state with some (1)MLCT/(3)MLCT character, which appears to have a larger (1)MLCT component than their bidentate and tridentate analogs. This results in a high radiative decay rate and high quantum yield for Pt(dpb)Cl and its analogs. However, the excited state properties of the Pt(N(∧)C(∧)N)X complexes are strongly dependent on the nature of the electron-accepting groups and substituents to the metal-phenyl fragment. A rational design will be needed to tune the emission energies of the Pt(N(∧)C(∧)N)X complexes over a wide range while maintaining their high luminescent efficiency.

A series of pi-conjugated compounds (1-23) were successfully synthesized by the Sonogashira, Suzuki, and Wittig-Horner reactions. The structure-property relationship about photoluminescence based on these synthesized compounds was systematically discussed in detail. In addition, energy gaps between ground and excited states of these compounds, which were in good agreement with the experimental observation, were calculated by the semiempirical parametrized PM3 method. It was revealed that emission efficiency largely depends on molecular structure, aggregation type, and size of nanoaggregates.

A dual-fluorescent donor-acceptor (D-A) dyad with tercarbazole (donor) and 2,3-dithienylmaleimide (acceptor) was synthesized and characterized. The emission intensity of long wavelength could be regulated by either bistable structures of the dyad or the polarities of solvents. By mimicking the function of an integrated logic gate, a 2-input AND logic operation is established. [reaction: see text].

A series of pi-conjugated compounds ending with dibenzosuberenylidene were synthesized efficiently. Their luminescence efficiencies were well-tuned by structural modification. Moreover, relative emission intensities were strongly affected by their existing appearances and exhibited aggregation-induced emission (AIE) behavior. Thus, emissions from nanoparticles, films, or powders were found to be more efficient than those from solutions. It demonstrated that these synthesized compounds might be practically used as fluorescent materials for potential optoelectronic applications.

2,7-Bis(4-dimethylaminophenyl)-9-(cycloheptatrienylidene)fluorene (1) was synthesized and characterized. 1 could be used as a fluorescent sensor either for pH or for pyridinium halide. Integrated with the ratiometric method and an NOR logic gate, a tunable two-input/multi-output system was presented on the basis of this single molecule. [structure: see text]

A series of 9-(cycloheptatrienylidene)fluorene derivatives were synthesized in good yields through the Suzuki or Sonogashira cross-coupling reactions. Fluorescence "off-on" behaviors of these compounds were investigated on the basis of variable acid concentrations. These compounds were shown to be acid-sensing fluorophores with utility as indicators in acidic environments.