Organic Interface Research Articles

Simultaneous determination of refined values of mobility, channel and contact resistance in organic field-effect transistors utilizing the four- and three-probe methods

Abstract Accurate determination of charge carrier mobility is a critical aspect in an organic field-effect transistor (OFET) as it is tightly correlated to the development of new materials, better device designs and improved fabrication methods. The presence of high contact resistance at the metal–organic semiconductor interface introduces an intrinsic error in the extraction of charge carrier mobility. In this report, electrical circuit analysis for the determination of the refined channel mobility, total contact resistance and channel resistance values is showcased for a poly(3-hexylthiophene) OFET with bottom-gate bottom-contact architecture. The process of determination is based on the combination of the conventional four-probe and three-probe measurement techniques. These two techniques are used in conjunction to assess refined mobility values in the channel region. This is followed by the determination of total contact resistance and channel resistances. The results show that, at a fixed drain current, mobility increases with the gate voltage while both the contact and channel resistances decrease.

Highly crystalline nanorods pyrene-based covalent organic framework artificial solid electrolyte interface accelerated interface Li+ regulation on lithium anode

The detrimental effects of heterogeneous Li deposition and aeolotropic Li dendrite propagation critically hamper its serviceability of Li metal batteries. The exploitation of neutral multifunctional porous polymer artificial SEI is imperative to modulate interfacial ionic transfer behavior. Herein, we propose a strategy based on dual-functional nanorod-shaped covalent organic frameworks (COF) to accelerate Li+ diffusion and mitigate lithium dendrite growth by creating an artificial solid electrolyte interface (SEI) layer. As anticipated, the immobilized high-polarity –OH and −CN- groups, along with the porous channel facilitates, facilitate uniform Li+ flux distribution and rapid Li+ migration. Additionally, the highly conjugated nature of the pyrene moiety not only enhances the plane π-π stacking crystallinity of TFDH-COF, but contributes positively to Li+ and repelling TFSI−. The combination of comprehensive ex-situ/in-situ characterizations and DFT calculations have unraveled the underlying mechanisms on the reductive Li mitigation energy barrier and enhancive Li+ transfer ability. In contrast with bare Li, the resultant TFDH-COF@Li electrode demonstrates the elevated reversibility of Li+ utilization, slight polarization, dendrite-free interface and prolonged cyclic performance in Li|Cu, Li|Li, and Li-based full cells operated at rigorous current densities. Those unswerving evidences enlighten the feasibility of engineering the neutrality COF layer to get rid of adverse disordered Li proliferation.

A metal–organic frameworks-imprinted emulsion interface with dynamic size- and site-selective recognition for significantly enhanced flavoniods extraction

The boronic acid suspended Cr based MIL-100 (MIL-100-B) sorbents have been widely used to separation of cis-diol containing molecules. However, it’s still challenging in fabrication of high performance metal organic frameworks (MOFs) due to its irregular size and low content of functional groups. For improving identification efficiency, the emulsion microreactor were firstly designed to purify MIL-100-B prior to their use. Herein, a highly ordered MOFs-imprinted polymer microsphere was synthesized by O/W Pickering emulsion template, which can highly selective separation of MIL-100-B via the synergistic effect of boronic acid sites and imprinted cavities. The obtained purified H-MIL-100-B exhibited the uniform size and abundant boronic acid groups (B elements ratio up to 27.37 %). The emulsion imprinted microsphere (EIMs) showed the good selectivity towards MIL-100-B. Additionally, the obtained MOF-imprinted microsphere exhibited green, convenient, sustainable separation process towards the purification and recycle of MIL-100-B. The purified MOFs (H-MIL-100-B) were used to specific bind with cis-diol flavoniods naringin (NRG). Satisfactorily, H-MIL-100-B show high adsorption amount (43.69μmol/g at 308 K), fast capture kinetics (160 min), high selectivity and excellent regenerability (up to seven cycles). Remarkably, the purified NRG solutions displayed lasting antibacterial activity against Staphylococcus aureus (S. aureus) with inhibition zone of 13.47 mm. More importantly, the H-MIL-100-B could effectively promote the specific recognition ability of NRG by reducing matrix interference and improving purification efficiency (93.93 %) from complex natural extracts. A high score (0.75) was predicted via analytical GREEnness (AGREE) approaches, demonstrating environmentally friendly and greenness of separation process. The MOFs-imprinted emulsion microspheres possessed dynamic recognition properties towards target MOFs, thus opening new direction for the development of convenient and efficient microreactor for the purification of other functional MOFs.

All Roads Lead to Rome: Isomers with Divergent Cathode Modification Mechanisms toward Ohmic Contact.

Cathode interfacial layers (CILs) hold utmost importance for achieving ohmic contact at the organic semiconductor-cathode interface of organic photovoltaic devices. Delving deep into diverse design principles and working mechanisms is of great significance for designing novel CILs with high performance. Herein, two novel nonamine-based CILs are designed: one featuring a cyclopentadiene unit, designated as CIL-cp; while the other, lacking cyclopentadiene, is referred to as CIL-ph, which is an isomer of CIL-cp. The subtle changes in chemical structures result in distinct modification mechanisms toward ohmic contact. On one hand, the robust electron-withdrawing characteristic of cyclopentadiene endows CIL-cp with lower energy levels, resulting in an interfacial dipole at the active layer-CIL-cp interface due to electron transfer from D18 to CIL-cp. On the other hand, CIL-ph exhibits a strong interfacial dipole at the CIL-Ag interface, which significantly reduces the work function (WF) of the silver electrode. Both CIL-cp and CIL-ph demonstrate excellent interfacial modification capability, whereas CIL-cp possesses a stronger electron extraction ability, thus leading to a high power conversion efficiency of 19.31% in the D18:L8-BO system. Our results reveal the distinctive operational mechanism of cyclopentadiene-based CILs, thus offering innovative design ideas for CIL materials.

Enhanced performance of perovskite solar cells with multifunctional organic interface conditioner

Regulation of interface defects and the extraction or transport of charge carriers are essential to enhance the stability and photovoltaic performance of perovskite solar cells (PSCs). A multifunctional intermediate layer of 2,7-dibromobenzo[1,2-b:6,5-b'] dithiophene-4,5-dione (DBO) is incorporated into PSCs. The small molecule of diverse functional groups facilitates intermolecular interactions that effectively mitigate the trap state, while it can form π-π stacking with 2,2′,7,7′-Tetrakis[N, N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-OMeTAD) to shorten the carrier transmission distance and expedite charge transfer. The introduction of molecular dipole moments can also change the work function (WF) and tune the energy level structure. Therefore, the optimized PSCs achieve a remarkable power conversion efficiency (PCE) of 23.43 % and demonstrate exceptional ambient stability. This study provides valuable insights for designing innovative small molecules as interface engineering, intending to further enhance device performance.

Boosting alkyne semi-hydrogenation selectivity via metal-organic interface modulated self-supporting palladium-based catalysts

The semi-hydrogenation of alkynes is crucial in the chemical industry, yet developing catalysts with both high activity and selectivity remains challenging. In this work, we introduced a self-supported method to fabricate a palladium-based nanocatalyst by in-situ reduction of Pd(II) on copper-based coordination polymers (Cu(I)-PNS) without external reducing agents. The resulting Pd/Cu(I)-PNS catalyst demonstrated exceptional efficiency and 94.8 % selectivity for styrene in the semi-hydrogenation of phenylacetylene, with no over-hydrogenation. Our findings highlight that the metal–organic interface enhances the catalyst’s selectivity by weakening styrene adsorption due to electronic modification. Additionally, the catalyst exhibited superior stability and activity, showing potential for various alkynes. This approach offers a direct and efficient strategy for creating highly selective palladium-based nanocatalysts for industrial applications.

Construction of COF/COF Organic S-Scheme Heterostructure for Enhanced Overall Water Splitting.

Covalent organic frameworks (COFs) as a new type of photocatalysts have shown unique advantages in visible-light-driven hydrogen evolution, while the reported overall water-splitting systems are still very rare among various COF-based photocatalysts. Herein, two COFs are integrated to construct a type of organic S-scheme heterojunction for improved overall water splitting. In this system, TpBpy-COF and COF-316 serve as H2- and O2-evolving components, respectively, which are combined through π-π interaction between conjugated aromatic rings. By introducing ultra-small Pt nanoparticles (NPs) into the pores of the TpBpy-COF nanosheets (NS), the resultant COF-316/Pt@TpBpy-COF NS heterostructure achieves extremely high H2 and O2 evolution rates of 220.4 and 110.2µmolg-1h-1, respectively, under visible light irradiation (λ ≥ 420nm). The results of transient absorption spectra (TAS) and photoelectronic measurements indicate that the organic heterojunction interface notably facilitates the separation and transfer of photogenerated electron-hole pairs. Further, theoretical calculations and in situ experiments confirm the spontaneous formation of the COF/COF heterojunction interface and the active sites for overall water splitting.

Fluorinated functional groups enhanced composite in-situ gel electrolytes for high voltage cathode of quasi solid-state lithium battery

Gel electrolyte is an ideal system for improving the cycling stability and safety of lithium metal battery. However, traditional gel system with acrylic ester system is still not suitable for high-voltage battery system limited by its intrinsic structure and unstable interface. The polymer structures with -CF3 modified acrylic ester are proposed to improve the stability of both structure and interface in high-voltage battery systems. The LiF-rich anode-electrolyte interface assisted by fluorine contained in-situ gel electrolyte ensures stable cycling of lithium anode. The quasi-solid state lithium battery assembled with the LiFePO4 can still achieve a capacity retention rate of 81.2 % after 900 cycles at a rate of 1 C. Furthermore, the uniform organic cathode-electrolyte interface constructed by crosslinked -CF3 modified polymer effectively inhibits the corrosion of HF on the cathode material. The interaction between the anion and solvent molecules prevents the continuous decomposition reaction of the electrolyte on the surface of the LiCoO2 cathode at high voltage, which guarantees LiCoO2 battery can still achieve a capacity retention rate of 82.1 % after 500 cycles at a voltage of 4.45V. Design of fluorine contained in-situ polymer gel electrolyte could promote the development of quasi solid-state battery in practical industrial application.

Scalable Synthesis of Organic Core/Shell Architectures toward Dual-Wavelength Optical Waveguides.

Organic core/shell heterostructures have undergone rapid progress in materials chemistry owing to the integration of a wide array of unique properties. Nonetheless, the intricate challenge of regulating homogeneous nucleation and phase separation processes in excessively analogous cocrystal structures presents a formidable barrier to expanding the synthesis strategy for organic core/shell heterostructures. Herein, we successfully achieved a phase separation growth process facilitated by the organic alloy interface layer through a dynamic visualization to capture the intricate morphological evolution. By finely regulating the nucleation process, homogeneous self-assembly induced by high chemical and structural compatibility is circumvented, enabling the formation of organic core/shell heterostructures. Notably, this core/shell architecture boasts dual-wavelength emission at 496 and 696 nm, accompanied by an optical loss coefficient of 0.092 dB per micrometer. This methodology shows potential for extending to the scalable design of other conformational cocrystal heterostructure systems, thereby offering valuable insights into the realm of organic photonics.

Evolution of surface and interface in soluble acene/polymer blends and its critical effects on gas diffusion dynamics in gas sensors

Organic field-effect transistor (OFET)-based gas sensors are highly valued for their sensitivity, cost-effectiveness, and operation at room temperature, making them ideal candidates for gas detection applications. For gas sensor performance, gas molecules must not only adsorb onto the organic semiconductor surface but also diffuse into the organic semiconductor-insulator interface that the conductive channel is formed. Therefore, the thickness of the active OSC layer is crucial in determining the efficiency of gas diffusion and the overall sensing response. This study analyzed the impact of semiconductor thin film thickness on gas sensing properties by adjusting the thickness of crystalline organic semiconductors. Using 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), known for its excellent response toward NO2, surface and interface characteristics were modulated through a blend approach. With all other conditions constant, the semiconductor film thickness significantly influenced NO2 detection properties, with the highest sensitivity observed in films around 10 nm thick. A quantitative analysis using Langmuir isotherms demonstrated that reducing the OSC layer thickness from 20 nm to 10 nm could enhance the response speed by a factor of five. Furthermore, the limit of detection (LOD) for TIPS-pentacene films at this reduced thickness was found to be in the low parts per billion (ppb) range.

Temperature-induced desorption and decomposition of the organic molecule on the fused silica surface: Cleaning mechanism of laser heating

Understanding the structure–property relationships of the organic molecule-fused silica interface at the molecular level provides insights into the nature of their adhesion and desorption. In this study, molecular dynamic simulation and the ReaxFF force field are employed to investigate the adhesion properties of benzene, toluene, dodecane and dibutyl phthalate (DBP) on fused silica at different temperatures. The result shows that adhesion energy between benzene or toluene molecules and fused silica decreases gradually with the increased system temperature. The temperature affects Coulomb and van der Waals forces significantly. Environmental humidity affects the evaporation rate of alkane contaminants from fused silica. Besides, ambient humidity also affects the number of alkane molecules adsorbed to the fused silica surface and the chain configuration of adsorbed alkane molecules. Although the coverage of alkane molecules on fused silica is different, the relationship between temperature and the amount of adsorbed alkane molecules is not affected by the surface coverage of alkane molecules on the fused silica surface. These findings provide theoretical support for removing transparent organic contaminants from glass-like material surfaces using laser heating, laying the theoretical foundation for developing laser cleaning technologies.

Electrical Double Layer and In Situ Polymerization SEI Enables High Reversible Zinc Metal Anode.

Aqueous zinc-ion batteries (AZIBs) stand out among new energy storage devices due to their excellent safety and environmental friendliness. However, the formation of dendrites and side reactions on the zinc metal anode during cycling have become the major obstacles to their commercialization. This study innovatively selected Sodium 4-vinylbenzenesulfonate (VBS) as a multifunctional electrolyte additive to address the issues. The dissociated VBS- anions can not only significantly alter the hydrogen bond network structure of H2O in the electrolyte, but also preferentially adsorb on the surface of the zinc anode before H2O molecules, which will result in the development of organic anion-rich interface and alterations to the electrical double layer (EDL) structure. Furthermore, the ─C═C─ structure in VBS leads to the formation of an in situ polymerized organic anion solid electrolyte interface (SEI) layer that adheres to the surface of the zinc anode. The mechanisms work together to significantly improve the performance of Zn//Zn symmetric batteries, achieving a cycle life of over 1800h at 1mA cm-2 and 1 mAh cm-2. The introduction of VBS also enhances the cycling performance and capacity of Zn//δ-MnO2 full cells. This study provides a low-cost solution for the development of AZIBs.

Transforming contaminant ligands at water–solid interfaces via trivalent metal coordination

In environmental matrices, the migration and distribution of contaminants at water–solid interfaces play a crucial role in their capture or dissemination. Scientists working in environmental remediation and wastewater treatment are increasingly aware of metal–contaminant coordination; however, interfacial behaviors remain underexplored. Here, we show that trivalent metal ions (e.g. Al3+ and Fe3+) mediate the migration of pollutant ligands (e.g. tetracycline (TC) and ofloxacin) to the organic solid interface. In the absence of Al3+, humic acid (HA) colloids (50 mg/L) capture 26.1 % of the TC in water (initial concentration: 10 mg/L) via weak intermolecular interactions (binding energy: −5.71 kcal/mol). Adding Al3+ (2.5 mg/L) significantly enhances the binding of TC to an impressive 94.2 % via Al3+ mediated coordination (binding energy: −84.89 kcal/mol). The significant increase in binding energy results in superior interfacial immobilization. However, excess free Al3+ competes for TC binding via direct binary coordination, as confirmed based on the unique fluorescence of Al3+–TC complexes. Density functional theory calculations reveal the intricate process of HA–Al3+ binding via carboxyl and phenolic hydroxyl sites. The HA–Al3+ flocs then leverage the remaining coordination capacity of Al3+ to chelate with TC. As well as providing insights into the pivotal role of metal ion on the self-purification of natural water bodies, our findings on the interfacial behavior of metal–contaminant coordination will propel coagulation technology to the capture of microscale pollutants.

Concentrated Chloride Electrolyte Enabling SEI for Fe Metal Anode

Iron is one of the most abundant metal elements in the Earth’s crust and has been widely used worldwide since ancient times. Due to this natural abundance and well-established mass production methods, iron is a promising candidate as a battery electrode for cost-effective large-scale energy storage systems. Edison’s Ni-Fe battery, invented in 1900, used an alkaline electrolyte without ferrous or ferric ions that eventually limited its anode design using iron oxide. More recent Fe redox flow batteries and the newly suggested Fe-ion batteries that use an acidic electrolyte containing ferrous ions (Fe2+) can utilize iron foil as an anode. Combining iron foil with Fe2+ electrolyte enables a simple design and faster kinetics on the anode side. However, introducing acidic electrolytes accelerates hydrogen evolution reaction (HER) on the iron surface. Severe HER affects cell performance in various ways, including lower Coulombic efficiency (CE), drying out of the electrolyte by water consumption, and precipitation of Fe2+ ions due to increased pH of the electrolyte. In this work, a concentrated chloride-based electrolyte was introduced to Fe-ion batteries to suppress HER and achieve a high-CE Fe2+/Fe electrode. With the help of nonpolar [ZnCl4]2- which enables low-polarity organic additives to be soluble in the aqueous solution, an organic solid electrolyte interface (SEI) can be formed on top of the electrode while plating iron. Fe anode protected by the SEI shows a noticeable decrease in HER during cycling, which leads to higher CE of more than 98% and twice longer cycle life.

Design of Janus Particles by Bipolar Electrochemistry at the Water–Organic Interface

Design of Janus Particles by Bipolar Electrochemistry at the Water–Organic Interface

Quantifying the interfacial tension of adsorbed droplets on electrified interfaces

HypothesisThis paper develops a new measurement method to answer the question: How does one measure the interfacial tension of adsorbed droplets? ExperimentsThis measurement is based on the placement of a bubble at a water|organic interface. To prove the concept, a bubble was formed by pipetting gas below the water|1,2-dichloroethane interface. Our values agree well with previous reports. We then extended the measurement modality to a more difficult system: quantifying interfacial tension of 1,2-dichloroethane droplets adsorbed onto conductors. Carbon dioxide was generated in the aqueous phase from the electro-oxidation of oxalate. Given carbon dioxide’s solubility in 1,2-dichloroethane, it partitions, a bubble nucleates, and the bubble can be seen by microscopy when driving the simultaneous oxidation of tris(bipyridine)ruthenium (II), a molecule that will interact with CO2.−. and provide light through electrochemiluminescence. We can quantify the interfacial tension of adsorbed droplets, a measurement very difficult performed with more usual techniques, by tracking the growth of the bubble and quantifying the bubble size at the time the bubble breaks through the aqueous|1,2-dichloroethane interface. FindingsWe found that the interfacial tension of nanoliter 1,2-dichloroethane droplets adsorbed to an electrified interface in water, which was previously immeasurable with current techniques, was one order of magnitude less than the bulk system.

Surface Segregated Monolayers of Fluoroalkylated Rod-like Molecule for Asymmetric Charge Transport at Organic Semiconductor Interfaces

Surface Segregated Monolayers of Fluoroalkylated Rod-like Molecule for Asymmetric Charge Transport at Organic Semiconductor Interfaces

Tailoring Mechanical Reliability in Transparent ZnO-Zincone Thin-Film Electrodes with Organic Interlayer Interfaces and Thickness.

To address the inherent brittleness of conventional transparent conductive oxides, researchers have focused on enhancing their flexibility. This is achieved by incorporating organic films to construct organic-inorganic hybrid layer-by-layer nanostructures, where the interlayer thickness and interface play pivotal roles in determining the properties. These factors are contingent on the type of material, processing conditions, and specific application requirements, making it essential to select the appropriate conditions. In this study, ZnO-zincone nanolaminate thin films were fabricated using atomic layer deposition and molecular layer deposition in various structural configurations. Transmission electron microscopy, X-ray diffraction, and scanning electron microscopy were used to conduct a thorough analysis of the thin-film growth and structural transformations resulting from the deposition conditions. Furthermore, the influence of structural differences at the interfaces on the mechanical properties of the films was investigated by employing both tensile and compression-bending fatigue tests. This comprehensive examination reveals noteworthy variations in the mechanical responses of the films. Thin films characterized by internal porosity and an intermixed amorphous structure demonstrated enhanced compressive toughness, whereas rigid organic layers improved flexibility. These findings offer valuable insights into the development of flexible, transparent multilayer films.

Hydrophobic and zincophilic organic hierarchical nano-membranes with ordered molecular packing for stable zinc metal anodes

Rechargeable aqueous Zn metal batteries hold significant potentials as one of the next-generation energy-storage devices due to their low cost and high safety. However, the uncontrollable dendrite growth and low efficiency in plating/stripping of Zn anodes hinder the commercial application of aqueous Zn-ion batteries (AZIBs). Herein, inspired by hydrophobic lotus, a multifunctional organic hierarchical nano-membrane serving as an artificial protective layer is constructed through the gas-liquid interface method, using self-assembled organic nanosheets (NOS). The organic nano-membrane exhibits ordered molecular packing, accompanied by uniform distribution of zincophilic carbonyl (CO) groups on the Zn metal surface. These groups function as active sites, homogenizing Zn2+ flux and accelerating Zn2+ deposition. Simultaneously, the hydrophobic membrane isolates active water, thereby restraining side reactions, effectively suppressing corrosion and extremely inhibiting dendrite growth. Consequently, NOS@Zn anode exhibits stable cycling over 2400 h and an average coulombic efficiency (CE) of 99.69 % (600 cycles) at 1 mA cm−2. Furthermore, NOS@Zn||CNT-MnO2 full cell presents remarkable capacity retention, approximately 5 times higher than that of Zn||CNT-MnO2 after 3000 cycles at 2 A g−1. This work develops an innovative organic interface modification material paving the way for dendrite-free Zn metal anodes and advancing the practical application of large-scale Zn-based energy storage systems.

Interface Visualization of Bio-material Interaction Via Cryo-AEM Using the Biosynthesis of Iron-Based Nanoparticles as a Model.

Although interaction between organisms and nonorganisms is vital in environmental processes, it is difficult to characterize at nanoscale resolution. Biosynthesis incorporates intracellular and extracellular processes involving crucial interfacial functions and electron and substance transfer processes, especially on the inorganic-organic interface. This work chooses the biosynthesis of iron-based nanoparticles (nFe) as a model for biomaterial interaction and employs Cryo-AEM (i.e., S/TEM, EELS, and EDS analysis based on sample preparation with cryo-transfer holder system), combined with CV, Raman, XPS, and FTIR to reveal the inorganic-organic interface process. The inorganic-organic interactions in the biosynthesis of iron-based nanoparticles by Shewanella oneidensis MR-1 (M-nFe) were characterized by changes in electron cloud density, and the corresponding chemical shifts of Fe and C EELS edges confirm that M-nFe acquires electrons from MR-1 on the interface. Capturing intact filamentous-like, slightly curved, and bundled structure provides solid evidence of a "circuit channel" for electron transfer between organic and inorganic interface. CV results also confirm that adding M-nFe can enhance electron transfer from MR-1 to ferric ions. A mechanism for the synthesis of M-nFe with MR-1 based on intracellular and extracellular conditions under facultative anaerobic was visualized, providing a protocol for investigating the organic-inorganic interface.