Poor Transport Properties Research Articles

Study on the preparation of stabilizer-free silymarin nanocrystals and its oral absorption mechanisms

Many researchers have studied the oral absorption mechanisms yet, however, considering stabilizers often participate in the absorption process of nanocrystals, these known mechanisms may be incorrect. Hence in this study, we aimed to explore the correct absorption mechanism of nanocrystals by performing related studies on stabilizer-free nanocrystals. We firstly prepared stabilizer-free silymarin nanocrystals by high-pressure homogenization, and then performed absorption-related studies, such as solubility, dissolution rate, pharmacokinetic study, cellular uptake and intracellular transport. Results showed the stabilizer-free silymarin nanocrystals had an average particle size of (450.2 ± 4.46) nm, with PDI of 0.280 ± 0.021 and Zeta potential of −26.9 ± 2.4 mV. The conversion of silymarin crude drug to stabilizer-free silymarin nanocrystals increased the compound's solubility by 1.41 times, with a dissolution rate of 92.2 % in water within 30 min compared to 38.5 % for crude drugs. Pharmacokinetic studies showed the oral bioavailability of stabilizer-free silymarin nanocrystals was found to be 1.48 times greater than that of the crude drugs. The cell experimentation results demonstrated that the stabilizer-silymarin nanocrystals can improve uptake but have poor transmembrane transport properties. Most researchers believe that nanocrystals can enhance transmembrane transport of drugs via an endocytosis-mediated pathway. In fact, nanocrystals are indeed endocytosed more by the cells, but this transport pathway is poor because the cells lack the intracellular transport pathway to transport nanocrystals from the AP side to the BP side. Therefore, we believe that the intracellular transport of nanocrystals can be enhanced by modifications and other carriers if needed to improve nanocrystals' ability to promote oral absorption.

Bimetal Fluorides with Adjustable Vacancy Concentration Reinforcing Ion Transport in Poly(ethylene oxide) Electrolyte.

The poor ambient ionic transport properties of poly(ethylene oxide) (PEO)-based SPEs can be greatly improved through filler introduction. Metal fluorides are effective in promoting the dissociation of lithium salts via the establishment of the Li-F bond. However, too strong Li-F interaction would impair the fast migration of lithium ions. Herein, magnesium aluminum fluoride (MAF) fillers are developed. Experimental and simulation results reveal that the Li-F bond strength could be readily altered by changing fluorine vacancy (VF) concentration in the MAF, and lithium salt anions can also be well immobilized, which realizes a balance between the dissociation degree of lithium salts and fast transport of lithium ions. Consequently, the Li symmetric cells cycle stably for more than 1400 h at 0.1 mA cm-2 with a LiF/Li3N-rich solid electrolyte interphase (SEI). The SPE exhibits a high ionic conductivity (0.5 mS cm-1) and large lithium-ion transference number (0.4), as well as high mechanical strength owing to the hydrogen bonding between MAF and PEO. The corresponding Li//LiFePO4 cells deliver a high discharge capacity of 160.1 mAh g-1 at 1 C and excellent cycling stability with 100.2 mAh g-1 retaining after 1000 cycles. The as-assembled pouch cells show excellent electrochemical stability even at rigorous conditions, demonstrating high safety and practicability.

Entropy engineering promotes thermoelectric performance while realizing P–N switchable conduction in BiSbSe1.5Te1.5

BiSbSe1.5Te1.5, a typical multi-layered compound, can be utilized to fabricate p-n junctions with the identical chemical composition by regulating the antisite defects and anion vacancies via defect engineering. However, the thermoelectric performance of n-type BiSbSe1.5Te1.5 is limited due to poor electrical transport properties. Entropy engineering is a novel strategy for expanding the space of performance optimization in materials science, including the field of thermoelectric. Herein, we realize a largely enhanced thermoelectric performance for n-type BiSbSe1.5Te1.5 by employing entropy engineering. Both mass field fluctuations and stress variations field are introduced simultaneously in the lattice, leading to additional phonon scattering. Moreover, nano-laminate structure, nanoscale interstices and holes are formed in the samples. All of these defects and nanoscale structures are especially efficient on trapping phonons. As a result, the optimizing electrical transport properties while maintaining low thermal conductivity are achieved, showcasing a peak ZT of 0.54 at 475 K and a remarkable average ZT of 0.45 between 300 and 550 K for n-type BiSbSe1.25Te1.75.These findings not only provide a way to enhance the thermoelectric performance of n-type BiSbSe1.5Te1.5 but also push forward the promise of the applications in fabricating well-matched p-n junctions using thermoelectric materials with the identical chemical composition.

Synergistic effect of oxygen vacancies and in-situ formed bismuth metal centers on BiVO4 as an enhanced bifunctional Li–O2 batteries electrocatalyst

Bismuth Vanadate (BiVO4) is a promising oxide-based photoanode for electrochemical applications, yet its practical use is constrained by poor charge transport properties, particularly under dark conditions. This study introduces a novel BiVO4 variant (Bi-BiVO4-10) that incorporates abundant oxygen vacancies and in-situ formed Bi metal, significantly enhancing its electrical conductivity and catalytic performance. Bi-BiVO4-10 demonstrates superior electrochemical performances compared to conventional BiVO4 (C-BiVO4), demonstrated by its most positive half-wave potential with the highest diffusion-limiting current in the oxygen reduction reaction (ORR) and earliest onset potential in the oxygen evolution reaction (OER). Notably, Bi-BiVO4-10 is explored for the first time as an electrocatalyst for lithium-oxygen (Li–O2) cells, showing reduced overcharge (610 mV) in the first cycle and extended cycle life (1050 h), outperforming carbon (320 h) and C-BiVO4 (450 h) references. The enhancement is attributed to the synergy of oxygen vacancies, Bi metal formation, increased surface area, and improved electrical conductivity, which collectively facilitate Li2O2 growth, enhance charge transport kinetics, and ensure stable cycling. Theoretical calculations reveal enhanced chemical interactions between intermediate molecules and the defect-rich surfaces of Bi-BiVO4-10, promoting efficient discharge and charge processes in Li–O2 batteries. This research highlights the potential of unconventional BiVO4-based materials as durable electrocatalysts and for broader electrochemical applications.

Synthesis of fluorene‐flanked diketopyrrolopyrrole‐based semiconducting polymers with thermocleavable side chains and their application in organic field effect transistors

AbstractThis study introduces the first fluorene‐flanked diketopyrrolopyrrole (FDPP)‐based semiconducting polymers, named Boc‐FDPP‐CoMs (CoM = TT or BT), synthesized via copolymerization of tert‐butoxycarbonyl (t‐Boc)‐substituted FDPP as the acceptor unit with thieno[3,2‐b]thiophene (TT) or bithiophene (BT) as the donor comonomers. The incorporation of t‐Boc groups addresses challenges related to poor solubility and polymer backbone twisting associated with the FDPP building block. While Boc‐FDPP‐CoMs demonstrate solubility in common organic solvents, facilitating favourable solution‐processability for uniform film fabrication, they exhibit significant backbone twisting, leading to poor charge transport properties. Post‐deposition thermal annealing at a mild temperature as low as 170°C conveniently removes t‐Boc groups. The resulting t‐Boc‐free copolymers, NH‐FDPP‐TT and NH‐FDPP‐BT, exhibit hole mobilities up to 5.0 × 10−3 and 2.2 × 10−3 cm2 V−1 s−1 in organic field effect transistors (OFETs), respectively, representing a substantial increase compared to their counterparts with t‐Boc groups. This study underscores a meticulously designed strategy for achieving solution solubility and backbone coplanarity through side‐chain engineering for FDPP and potentially other sterically demanding building blocks to construct high‐performance semiconducting polymers for OFETs and other applications.

External Electric Field Control of Exciton Motion in Porphyrin-Based Metal Organic Frameworks.

Porphyrins are excellent light-harvesting complexes. Presently they are unsuitable for photovoltaic applications, as their excellent light absorbance is compensated to a large extent by their poor transport properties, where most excitons are lost by recombination. Arranging porphyrins in regular, strongly bound, lattices of surface-anchored metal-organic frameworks (PP-SURMOFs) may facilitate charge carrier dissociation, but does not significantly enhance the conductive properties. In most cases, photogenerated excitons traverse undirected, Brownian motion through a hopping process, resulting in a substantial diffusion length to reach electrodes, leading to significant exciton loss through recombination. Here, we propose to guide exciton diffusion indirectly by an external electric field. We show that electric fields, even as strong as 1 V nm-1, do not affect the HOMO-LUMO gap of the porphyrins. However, fields of 0.1 V nm-1 and even less demonstrate a notable Stark effect, with slight band gap reductions, for some PP-SURMOFs. When applied as an electric field gradient, for instance, via the substrate, it creates a unidirectional hopping pathway for the excitons. Consequently, we expect a significant reduction of exciton diffusion length leading to increased utilization of photogenerated excitons as they reach the electrodes. This strategy holds promise for integrating photoactive molecules in photovoltaic and photocatalytic applications.

14-Electron Redox Chemistry Enabled by Salen-Based π-Conjugated Framework Polymer Boosting High-Performance Lithium-Ion Storage.

A paucity of redox centers, poor charge transport properties, and low structural stability of organic materials obstruct their use in practical applications. Herein, these issues have been addressed through the use of a redox-active salen-based framework polymer (RSFP) containing multiple redox-active centers in π-conjugated configuration for applications in lithium-ion batteries (LIBs). Based on its unique architecture, RSFP exhibits a superior reversible capacity of 671.8 mAh g-1 at 0.05 A g-1 after 168 charge-discharge cycles. Importantly, the lithiation/de-lithiation performance is enhanced during operation, leading to an unprecedented reversible capacity of 946.2 mAh g-1 after 3500 cycles at 2 A g-1. The structural evolution of RSFP is studied ex situ using X-ray photoelectron spectroscopy, revealing multiple active C═N, C─O, and C═O sites and aromatic sites such as benzene rings. Remarkably, the emergence of C═O originated from C─O is triggered by an electrochemical process, which is beneficial for improving reversible lithiation/delithiation behavior. Furthermore, the respective strong and weak binding interactions between redox centers and lithium ions, corresponding to theoretical capacities of 670.1 and 938.2 mAh g-1, have been identified by density functional theory calculations manifesting 14-electron redox reactions. This work sheds new light on routes for the development of redox-active organic materials for energy storage applications.

Enhanced performance and stability of quasi two-dimensional perovskite solar cells by conductive phosphine oxide

Recently, quasi two-dimensional (quasi-2D) perovskite solar cells (PSCs) have been paid more attentions due to their good stability. While the efficiency of 2D PSCs is lower than that of 3D ones due to their poor charge transport property. Here we introduced a conductive material of 2,7-bis(diphenylphosphoryl)-9,9′-spirobifluorene (SPPO13) into the precursor solution of quasi-2D perovskite GAMA5Pb5I16 (GA = guanidinium, MA = methylammonium) to improve the charge transfer property. The efficiency of the PSCs with SPPO13 is increased to 18.58 % from 16.97 % for the control, which is resulting from the enlarged grain size, increased electrical conductivity, and reduced trap state density induced by the addition of SPPO13. Moreover, the additon of SPPO13 improves the stability of the devices. The normalized PCE of the devices with SPPO13 keeps 90 % of the original value after aging for 30 days in atmosphere. This study provides a novel way to enhance the charge transfer property of 2D perovskite by conductive material for enhanced efficiency and stability of quasi-2D PSCs.

High-Performance Organic Field-Effect Transistors Based on Two-Dimensional Vat Orange 3 Crystals

The exploration and research of low-cost, environmentally friendly, and sustainable organic semiconductor materials are of immense significance in various fields, including electronics, optoelectronics, and energy conversion. Unfortunately, these semiconductors have almost poor charge transport properties, which range from ∼ 10−4 cm2⋅V−1⋅s−1 to ∼ 10−2 cm2⋅V−1⋅s−1. Vat orange 3, as one of these organic semiconductors, has great potential due to its highly conjugated structure. We obtain high-quality multilayered Vat orange 3 crystals with two-dimensional (2D) growth on h-BN surfaces with thickness of 10–100 nm using physical vapor transport. Raman’s results confirm the stability of the chemical structure of Vat orange 3 during growth. Furthermore, by leveraging the structural advantages of 2D materials, an organic field-effect transistor with a 2D vdW vertical heterostructure is further realized with h-BN encapsulation and multilayered graphene contact electrodes, resulting in an excellent transistor performance with On/Off ratio of 104 and high field-effect mobility of 0.14 cm2⋅V−1⋅s−1. Our results show the great potential of Vat orange 3 with 2D structures in future nano-electronic applications. Furthermore, we showcase an approach that integrates organic semiconductors with 2D materials, aiming to offer new insights into the study of organic semiconductors.

Br doping-induced evolution of the electronic band structure in dimorphic and hexagonal SnSe2 thermoelectric materials.

SnSe2 with its layered structure is a promising thermoelectric material with intrinsically low lattice thermal conductivity. However, its poor electronic transport properties have motivated extensive doping studies. Br doping effectively improves the power factor and converts the dimorphic SnSe2 to a fully hexagonal structure. To understand the mechanisms underlying the power factor improvement of Br-doped SnSe2, the electronic band parameters of Br-doped dimorphic and hexagonal SnSe2 should be evaluated separately. Using the single parabolic band model, we estimate the intrinsic mobility and effective mass of the Br-doped dimorphic and hexagonal SnSe2. While Br doping significantly improves the mobility of dimorphic SnSe2 (with the dominant hexagonal phase), it results in a combination of band convergence and band flattening in fully hexagonal SnSe2. Br-doped dimorphic SnSe2 is predicted to exhibit higher thermoelectric performance (zT ∼0.23 at 300 K) than Br-doped fully hexagonal SnSe2 (zT ∼0.19 at 300 K). Characterisation of the other, currently unidentified, structural phases of dimorphic SnSe2 will enable us to tailor the thermoelectric properties of Br-doped SnSe2.

Prodrug Approach: NSAID Conjugates of Platinum Compounds as Anti-Cancer Agents

Prodrug based synthetic approach is a very promising area of research to enhance the pharmaco–kinetic and pharmaco-dynamic properties of the drugs with the remarkable reduction of the side effects. Prodrug can be used for drugs which are having poor solubility, poor transport properties, production of chronic side effects thus this approach provides a powerful tool for novel drug conjugate with improved therapeutic value. Platinum based anti-neoplastic agents are widely used in chemotherapeutic regimen but the side effects like hepatotoxicity, ototoxicity, cardiotoxicity, nausea and vomiting, diarrhea, mucositis, stomatitis, pain, alopecia, anorexia, cachexia, cytopenias and asthenia were reported. So the development of prodrugs by using platinum compounds and Non-steroidal anti-inflammatory drugs showed better therapeutic value with the reduction of side effects. Non-steroidal anti-inflammatory drugs are broad class of drugs showed Analgesic, Anti–inflammatory and Anti-pyretic activities based on the mechanism of cyclooxygenase (cox-1 and cox-2) enzyme inhibition and formation of prostaglandins. Also Non-steroidal anti-inflammatory drugs have different targets to elicit various pharmacological actions and are beneficial for many other diseases. The different targets are nuclear factor kappa B(NF-Κb), Peroxisome proliferator-activated receptors(PPAR), Mammalian target of rapamycin(mTOR), Autophagy, Cytochrome c, NSAID activated gene (NAG-1), Angiogenesis, Resolvins, Protectins, Maresins. This review focused on the development of platinum prodrugs by conjugating with different NSAIDs and the therapeutic applications of the developed novel molecules including dual action and triple action prodrugs. This review discussed the different aspects of prodrug based approach, Detail mechanism and other molecular targets of NSAIDs and the development of the platinum compounds –NSAID prodrugs.

Charge Carrier Trapping in the Surface Region of BiVO4 Photoanodes

Photoelectrochemical water splitting is a promising method for converting solar energy into chemical energy stored in molecular hydrogen and oxygen. However, the efficiency of this process is heavily dependent on the properties of the photoelectrode materials used. Metal oxide semiconductors, such as BiVO4, are commonly used as photoanode materials, but they have poor charge transport properties and surface catalytic activity, which can limit their efficiency.To address these limitations, catalysts are often incorporated onto the surface of the photoanode to improve its surface activity. However, the overall efficiency of the photoelectrochemical process is also influenced by charged defect sites present both in the bulk and on the surface of the semiconductor. These defect sites can trap charges and hamper the kinetics of the process in the millisecond time scale. To address this issue, covalently coordinated catalyst layers and surface doping can be used to eliminate these trapped charges. Moreover, the bulk charge carriers are not entirely decoupled from the surface processes and can be influenced by surface treatments. Therefore, a multi-folded approach that considers both the surface and bulk properties of the photoanode, as well as the role of the catalysts, is necessary to improve the overall efficiency of photoelectrochemical water splitting.We have investigated interfacial charge trapping and transfer processes through a CoOx catalyst layer deposited on BiVO4 by atomic layer deposition (ALD) and cobalt incorporated into the subsurface region. We have shown, by the combination of activity studies and spectroscopy investigations, that oxygen vacancies modified by cobalt incorporation have a remarkable impact on the water oxidation activity and charge injection efficiency. We further demonstrated by transient photocurrent measurements performed by fast LED light pulses (within ms time scale) that the CoOx catalyst layer reduced the number of trapped electrons and improved the rate of charge utilization. Cobalt ions in the subsurface region on the other did not act as catalytic centers but they eliminated the trapping process. We have also confirmed these observations by transient absorption spectroscopy investigations and showed that cobalt incorporation had a much bigger effect on the charge recombination lifetime.

An Electrochemical Cell for Operando Grazing-Incidence X-Ray Absorption Spectroscopic Studies of Low-Loaded Electrodes

X-ray absorption spectroscopy (XAS) is a powerful technique that can provide element specific information on the local electronic and structural properties of newly developed electrocatalysts, especially when performed under operating conditions (i.e., operando). However, the large amounts of catalyst typically needed to achieve sufficiently high spectral quality and temporal resolution can result in working electrodes of several micrometers in thickness. This can in turn lead to an inhomogeneous potential distribution across the electrode, delamination and/or incomplete utilization of the catalyst layer, severe bubble formation and accumulation due to poor mass transport properties.[1, 2] In addition, the activity and selectivity of a catalyst are often measured in a different cell geometry (e.g., using rotating disk electrodes (RDEs)), leading to uncertainties in comparison with the results inferred from spectroscopic data.[3]To tackle these problems we have developed a new spectroelectrochemical XAS flow cell that enables spectral acquisition in fluorescence mode using an X-ray beam incidence angle of ≤ 0.1° with regards to the working electrode’s substrate plane, i.e., in a so called grazing incidence (GI) configuration (see Figure 1). In this acquisition configuration we successfully tracked the formation of palladium hydride with a time resolution of 10 seconds per spectrum while using a Pd-loading as low as 50 µgPd∙cm-2. Moreover, the careful design of the working electrode flow field allows the study of faradaic processes (e.g., O2-reduction) under mass-transport controlled conditions entailing currents comparable to those attained in RDE measurements (≤ 10 mA∙cm−2). The combination of these features with an ion-conductive membrane to separate the working- and counter-electrode compartments additionally enables the detection of gaseous products (e.g., from CO2-electroreduction) by degassing them out of the electrolyte and analyzing them in time-resolved fashion by means of mass spectrometry.[4] References Diklić, N., et al., Potential Pitfalls in the Operando XAS Study of Oxygen Evolution Electrocatalysts. ACS Energy Letters, 2022. 7(5): p. 1735-1740. Diercks, J.S., et al., Spectroscopy vs. Electrochemistry: Catalyst Layer Thickness Effects on Operando/In Situ Measurements. Angew Chem Int Ed Engl, 2023: p. e202216633. Diercks, J.S., et al., Interplay between Surface-Adsorbed CO and Bulk Pd Hydride under CO2-Electroreduction Conditions. ACS Catalysis, 2022: p. 10727-10741. Khanipour, P., et al., Electrochemical Real-Time Mass Spectrometry (EC-RTMS): Monitoring Electrochemical Reaction Products in Real Time. Angew Chem Int Ed Engl, 2019. 58(22): p. 7273-7277 Figure 1

Dimensional and Optoelectronic Tuning of Lead-free Perovskite Cs3 Bi2 I9-n Brn Single Crystals for Enhanced Hard X-ray Detection.

Inorganic Bi-based perovskites have shown great potential in X-ray detection for their large absorption to X-rays, diverse low-dimensional structures, and eco-friendliness without toxic metals. However, they suffer from poor carrier transport properties compared to Pb-based perovskites. Here, we propose a mixed-halogen strategy to tune the structural dimensions and optoelectronic properties of Cs3 Bi2 I9-n Brn (0≤n≤9). Ten centimeter-sized single crystals are successfully grown by the Bridgman technique. Upon doping bromine to zero-dimensional Cs3 Bi2 I9 , the crystal transforms into a two-dimensional structure as the bromine content reaches Cs3 Bi2 I8 Br. Correspondingly, the optoelectronic properties are adjusted. Among these crystals, Cs3 Bi2 I8 Br exhibits negligible ion migration, moderate resistivity, and the best carrier transport capability. The sensitivities in 100 keV hard X-ray detection are 1.33×104 and 1.74×104 μC Gyair -1 cm-2 at room temperature and 75 °C, respectively, which are the highest among all reported bismuth perovskites. Moreover, the lowest detection limit of 28.6 nGyair s-1 and ultralow dark current drift of 9.12×10-9 nA cm-1 s-1 V-1 are obtained owing to the high ionic activation energy. Our work demonstrates that Br incorporation is an effective strategy to enhance the X-ray detection performance by tuning the dimensional and optoelectronic properties.

Dimensional and Optoelectronic Tuning of Lead‐free Perovskite Cs3Bi2I9−nBrn Single Crystals for Enhanced Hard X‐ray Detection

AbstractInorganic Bi‐based perovskites have shown great potential in X‐ray detection for their large absorption to X‐rays, diverse low‐dimensional structures, and eco‐friendliness without toxic metals. However, they suffer from poor carrier transport properties compared to Pb‐based perovskites. Here, we propose a mixed‐halogen strategy to tune the structural dimensions and optoelectronic properties of Cs3Bi2I9−nBrn (0≤n≤9). Ten centimeter‐sized single crystals are successfully grown by the Bridgman technique. Upon doping bromine to zero‐dimensional Cs3Bi2I9, the crystal transforms into a two‐dimensional structure as the bromine content reaches Cs3Bi2I8Br. Correspondingly, the optoelectronic properties are adjusted. Among these crystals, Cs3Bi2I8Br exhibits negligible ion migration, moderate resistivity, and the best carrier transport capability. The sensitivities in 100 keV hard X‐ray detection are 1.33×104 and 1.74×104 μC Gyair−1 cm−2 at room temperature and 75 °C, respectively, which are the highest among all reported bismuth perovskites. Moreover, the lowest detection limit of 28.6 nGyair s−1 and ultralow dark current drift of 9.12×10−9 nA cm−1 s−1 V−1 are obtained owing to the high ionic activation energy. Our work demonstrates that Br incorporation is an effective strategy to enhance the X‐ray detection performance by tuning the dimensional and optoelectronic properties.

A Combined Theoretical and Experimental Investigation of 3D Ternary Perovskite‐Like Silver Iodobismuthate

AbstractLead‐free ternary bismuth halide perovskites A3Bi2X9 have gained much attention as a solution for toxic and unstable lead halide perovskites due to their facile solution processability, high optical absorption coefficient, and high stability. However, their photovoltaic performance remains poor due to their wide bandgap (∼2 eV), and poor charge transport properties stem from their low‐dimensional crystal structure. To promote the 3D structure and reduce the bandgap of ternary Bi‐halide perovskites, we replace the alkali elements at the A‐site with the transition element Ag+ to obtain a new class of perovskite‐like materials named rudorffites AgaBibIa+3b. We investigated the photophysical properties of AgBiI4 by a combined theoretical and experimental approach. Our DFT‐PBE‐SOC predicted band gap for cubic defect spinel AgBiI4 is 2.01 eV, while that obtained for spin‐coated AgBiI4 film is 1.67 eV. Furthermore, the strong p‐p band edge transition leads to high optical absorption in this material. Finally, a photodetector device fabricated using AgBiI4 shows excellent photoresponsivity (183 μA/W) and detectivity (20.93×108 Jones) with a fast rise/decay time of 0.27 s/0.29 s. This newly explored semiconductor class can be a promising and stable choice for advanced optoelectronic devices.

Low-Temperature Cross-Linkable Hole Transport Materials for Solution-Processed Quantum Dot and Organic Light-Emitting Diodes with High Efficiency and Color Purity.

Cross-linkable hole transport materials (HTMs) are ideal for improving the performance of solution-processed quantum dot light-emitting diodes (QLEDs) and phosphorescent light-emitting diodes (OLEDs). However, previously developed cross-linkable HTMs possessed poor hole transport properties, high cross-linking temperatures, and long curing times. To achieve efficient cross-linkable HTMs with high mobility, low cross-linking temperature, and short curing time, we designed and synthesized a series of low-temperature cross-linkable HTMs comprising dibenzofuran (DBF) and 4-divinyltriphenylamine (TPA) segments for highly efficient solution-processed QLEDs and OLEDs. The introduction of divinyl-functionalized TPA in various positions of the DBF core remarkably affected their chemical, physical, and electrochemical properties. In particular, cross-linked 4-(dibenzo[b,d]furan-3-yl)-N,N-bis(4-vinylphenyl)aniline (3-CDTPA) exhibited a deep highest occupied molecular orbital energy level (5.50 eV), high hole mobility (2.44 × 10-4 cm2 V-1 s-1), low cross-linking temperature (150 °C), and short curing time (30 min). Furthermore, a green QLED with 3-CDTPA as the hole transport layer (HTL) exhibited a notable maximum external quantum efficiency (EQEmax) of 18.59% with a remarkable maximum current efficiency (CEmax) of 78.48 cd A-1. In addition, solution-processed green OLEDs with 3-CDTPA showed excellent device performance with an EQEmax of 15.61%, a CEmax of 52.51 cd A-1, and outstanding CIE(x, y) color coordinates of (0.29, 0.61). This is one of the highest reported EQEs and CEs with high color purity for green solution-processed QLEDs and OLEDs using a divinyl-functionalized cross-linked HTM as the HTL. We believe that this study provides a new strategy for designing and synthesizing practical cross-linakable HTMs with enhanced performance for highly efficient solution-processed QLEDs and OLEDs.

Organic Electrochemical Transistor Based on Hydrophobic Polymer Tuned by Ionic Gels

AbstractHydrophobic conjugated polymers have poor ionic transport property, so hydrophilic side chains are often grafted for their application as organic electrochemical transistors (OECTs). However, this modification lowers their charge transport ability. Here, an ionic gel interfacial layer is applied to improve the ionic transport while retaining the charge transport ability of the polymers. By using the ionic gels comprising gel matrix and ionic liquids as the interfacial layers, the hydrophobic polymer achieves the OECT feature with high transconductance, low threshold voltage, high current on/off ratio, short switching time, and high operational stability. The working mechanism is also revealed. Moreover, the OECT performance can be tuned by varying the types and ratios of ionic gels. With the proposed ionic gel strategy, OECTs can be effectively realized with hydrophobic conjugated polymers.

Organic Electrochemical Transistor Based on Hydrophobic Polymer Tuned by Ionic Gels.

Hydrophobic conjugated polymers have poor ionic transport property, so hydrophilic side chains are often grafted for their application as organic electrochemical transistors (OECTs). However, this modification lowers their charge transport ability. Here, an ionic gel interfacial layer is applied to improve the ionic transport while retaining the charge transport ability of the polymers. By using the ionic gels comprising gel matrix and ionic liquids as the interfacial layers, the hydrophobic polymer achieves the OECT feature with high transconductance, low threshold voltage, high current on/off ratio, short switching time, and high operational stability. The working mechanism is also revealed. Moreover, the OECT performance can be tuned by varying the types and ratios of ionic gels. With the proposed ionic gel strategy, OECTs can be effectively realized with hydrophobic conjugated polymers.

Fast solvent evaporation of phase pure CuBi2O4 photocathodes for photoelectrocatalytic water splitting

P-type metal oxide semiconductor CuBi2O4 exhibits excellent energy band structures and photoelectric response characteristics, which are critical for photoelectrocatalytic water splitting. However, the photocurrent densities are still well below the theoretical limit due to poor charge carrier separation and transport properties. In this work, we report a synthetic method for the preparation of phase-pure CuBi2O4 photocathode films via spray pyrolysis by adjusting the evaporation rate of the atomized droplets. An increase in the evaporation rate of the solvent may fix the structure of the deposited film faster and decrease the time available for the establishment of the segregation gradient, thus producing phase-pure semiconductor films. This method reduces process complexity and cost, and the applicability of spray pyrolysis for the preparation of phase-pure CuBi2O4 films is also confirmed. In addition, the photoelectrochemical evaluation of the samples prepared under different treatment conditions reveals that hole transport critically affects the photoelectrocatalytic performance of CuBi2O4 photocathodes. CuO can be used as a hole transport layer to promote the collection and transfer of holes and reduce the recombination of photogenerated carriers.