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Interface engineering is widely used to enhance the efficiency and stability of photodetectors (PDs). Although fluorine-containing materials are ideal for interface modification, they are seldom used at the NiOx/perovskite interface. This paper reports on the use of Tris(pentafluorophenyl)borane (BCF) and 2,3,5,6-tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4-TCNQ)-modified NiOx HTL to achieve high-efficiency and high-stability PDs. This study shows that BCF and F4-TCNQ interact to provide better doping ability, form Lewis adducts with Pb2+, and enhance the crystallinity of their perovskites. Interaction with nickel oxide optimizes the Ni3+/Ni2+ ratio, thus improving conductivity and charge transport capability. The F4-TCNQ:BCF modification effectively reduces interface defects, improves carrier mobility, and enhances both the performance and stability of PDs in ambient air. The detector achieves a maximum EQE value of 89.4%, a dark current density of 1.51 × 10−10A cm−2, a detectivity of 6.33 × 1013 Jones, and a LDR of 133.4 dB. Additionally, the interfacially modified device maintains over 90% of its initial performance after one month of storage in ambient air. Our results highlight the importance of F4-TCNQ:BCF interface modification and provide a reference for the further research and development of perovskite devices. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A novel macrocycle based on conformation‐adaptive and electron‐rich dihydrophenazine was designed and synthesized. On the one hand, the macrocycle showed host‐guest interactions with tetracyanoquinodimethane (TCNQ) driving by charge transfer interaction between them. Meanwhile, host‐guest complexation was accompanied by fluorescence quenching and conformational change of the macrocycle. On the other hand, the oxidation of the macrocycle resulted in its diradical cation analogue and induced the release of the guest molecule TCNQ, thereby accomplishing reversible binding dynamics. Therefore, this work well illustrates the chemical and structural versatility of dihydrophenazine in the synthesis of macrocycles and their host‐guest chemistry. [ABSTRACT FROM AUTHOR]

Complex (Cp3CeIV)2(TCNQ)(CeIIICp3)2 (1) was prepared by reducing neutral TCNQ0 (tetracyanoquinodimethane) with Cp3Ce(THF). Two types of cerium centres with a dianionic TCNQ2− moiety are present in 1, wherein each of the four cyano-groups are bound by a cation. Formation of this trapped-valent organocerium compound 1 is facilitated by metal–ligand redox cooperativity. Characterization of 1 was carried out using structural-, magnetometry-, and IR-spectroscopic analyses. Photophysical studies on this compound reveal CeIII luminescence, and opens up avenues for promising multifunctional, mixed-valent lanthanide materials. [ABSTRACT FROM AUTHOR]

In this review article, the synthesis, characterization and physico‐chemical properties of the organic donor‐acceptor complexes are highlighted and a special emphasis has been placed on developing them as semiconducting materials. The electron‐rich molecules, i. e., donors have been broadly grouped in three categories, namely polycyclic aromatic hydrocarbons, nitrogen heterocycles and sulphur containing aromatic donors. The reactions of these classes of the donors with the acceptors, namely tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), tetracyanobenzene (TCNB), benzoquinone, pyromellitic dianhydride and pyromellitic diimides, fullerenes, phenazine, benzothiadiazole, naphthalimide, DMAD, maleic anhydride, viologens and naphthalene diimide are described. The potential applications of the resulting DA complexes for physico‐electronic purposes are also included. The theoretical investigation of many of these products with a view to rationalise their observed physico‐chemical properties is also discussed. [ABSTRACT FROM AUTHOR]

The development of sensor electrode materials for the detection of metabolites will enable point‐of‐care diagnostic devices for the monitoring and treatment of metabolic diseases such as diabetes. Current state‐of‐the‐art glucose sensing electrodes employ the organic salt tetrathiafulvene tetracyanoquinodimethane (TTF TCNQ) to receive electrons directly from enzymatic reactions of glucose. However, TTF TCNQ is insoluble in most solvents, making it challenging to deposit high‐quality electrodes. Furthermore, its hydrophobicity hinders its interface with aqueous solutions in physiological environments. To overcome these issues, TCNQ derivatives are introduced into an electron‐rich and hydrophilic conjugated polymer. Thus, a polymeric electrode is demonstrated that is easily solution processible and can undergo volumetric direct electron transfer with glucose reactions throughout its bulk. This study further elucidates the electron transfer mechanism during chemical doping and metabolite sensing reactions to inform general design rules for this new class of glucose sensing materials. [ABSTRACT FROM AUTHOR]

A series of xylene charge-transfer complexes with fluorine-substituted tetracyanoquinodimethane (TCNQ) acceptors were studied experimentally and theoretically in order to reveal the role of various intermolecular interactions on stoichiometry and the crystal structure. It was shown that o-xylene face-to-face donor–donor interactions became significant enough to result in the formation of 2:1 cocrystals with F1TCNQ and F4TCNQ irrespective of growth conditions. The supramolecular arrangement in these cocrystals is mainly determined by the number of fluorine atoms in the acceptor. Comparative DFT and MP2 calculations of the pairwise intermolecular interactions revealed the overestimation of the dispersion energy for these systems by the DFT-wB97XD approach. [ABSTRACT FROM AUTHOR]

The current work reports the effect of palladium nanoparticles and their nanogeometry on the redox electrochemistry of tetracyanoquinodimethane (TCNQ) modified electrodes. Palladium nanoparticles were prepared with different concentrations of 3-aminopropyltrimethoxysilane and calcination at 600 °C to yield PdNP-1 and PdNP-2 of the average size of 1 µm and 12 nm, respectively. The palladium nanoparticles were characterized by TEM, XRD, and AFM techniques. The electrochemical excellence of ascorbic acid was resoluted using cyclic voltammetry amperometry, electrochemical impedance spectroscopy, and differential pulse voltammetry. A limit of detection (LOD) was found to be 51.61, 44.38 and 30.10 µM over a linear range from 50 to 625 µM for modified CPE/TCNQ, CPE/TCNQ-PdNP-1, and CPE/TCNQ-PdNP-2, respectively, determined by amperometric analysis for ascorbic acid at pH 7. The synergistic effect of Palladium and π* orbital of TCNQ played an important role in the enhancement of the catalytic activity of the modified electrode. The modified electrode showed good sensitivity, stability, and reproducibility which was confirmed by cyclic voltammetry, and amperometric analysis. The charge transfer resistance value also indicated that the modified electrode hads good electrocatalytic activity. [ABSTRACT FROM AUTHOR]

Chemically altering molecules can have dramatic effects on the physical properties of a series of very similar molecular compounds. A good example of this is within the quasi-1D spin-Peierls system potassium TCNQ (TCNQ = 7,7,8,8-tetracyanoqunidimethane), where substitution of TCNQF 4 for TCNQ has a dramatic effect on the 1D interactions, resulting in a drop in the corresponding spin-Peierls transition temperature. Within this work, we extend the investigation to potassium TCNQBr 2 , where only two protons of TCNQ can be substituted with bromine atoms due to steric constraints. The new system exhibits evidence for a residual component of the magnetism when probed via magnetic susceptibility measurements and muon spin spectroscopy. The observations suggest that the system is dominated by short range, and potentially disordered, correlations within the bulk phase. [ABSTRACT FROM AUTHOR]

Abstract We report the electronic absorption spectroscopy of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and its fluorinated derivatives (F2TCNQ and F4TCNQ), well-known electron-accepting molecules in common organic solvents (toluene, chlorobenzene, acetonitrile, and ethanol) under controlled exposure to air (O2) and UV light. All compounds (FxTCNQ (x = 0, 2, 4)) were stable in a neutral state (FxTCNQ0) in toluene and chlorobenzene, even under both O2 and UV light. On the other hand, in EtOH, the formation of FxTCNQ·− was monitored upon controlled exposure to O2 or UV light. Especially in air-equilibrated ethanol upon the UV-illumination, efficient α,α-dicyano-p-toluoylcyanide anion (DCTC−) and its fluorinated derivatives were generated evinced by the absorption peak near 480 nm, whereas the reaction was shut off by removing O2 or blocking UV light, thereby keeping FxTCNQ·− stable. However, even in deaerated ethanol, upon the UV-illumination, the anion formation of TCNQ and its fluorinated derivatives (FxTCNQ·−, x = 0, 2, 4) was inevitable, showing the stability of FxTCNQ0 depends on the choice of solvent.

The TCNQ-rGO hybrid with connected conductive network exhibits the potential application in aqueous ammonium ion batteries. [Display omitted] Lithium-ion batteries (LIBs) have received much attention because of their environmental, financial, and safety concerns. The advantages of aqueous electrochemical energy storage include environmental friendliness and safety, and the development of prepared electrode materials is predicted to alleviate these issues. A redox-active organic compound, 7,7,8,8‑tetracyanoquinodimethane (TCNQ), is a suitable electrode for aqueous batteries. In this work, the porous and electronic interconnected structure of TCNQ is designed by electronic modulation and structure engineering. With the reduced graphene oxide (rGO) in situ homogeneous loading TCNQ by a one-step facile approach, the exquisite architecture has enhanced conductivity and connected conductive networks, favoring the storage and transportation of NH 4 + or electrons in aqueous electrolytes. As a cathode, the obtained TCNQ-rGO exhibits superior performance for NH 4 + batteries with an improved reversible capacity of 92.7 mAh/g at 1 A/g of quadruple capacity boosting to pure TCNQ and stable cycle life (5000 cycles at 10 A/g). The adjustment of the loading ratio of TCNQ and rGO for the cycling performance has been studied in detail. Furthermore, the superior ammonium storage mechanism of the TCNQ-rGO hybrid is thoroughly discussed by in situ Raman or ex situ measurements, which also determine the redox activity center groups of the TCNQ-rGO hybrid. Energy level calculations are conducted to help illustrate its potential as an electrode material. Our work demonstrates that electronic modulation and structural engineering of TCNQ can improve the electrochemical performance of molecular organic compound-based electrodes for aqueous rechargeable batteries in a simple and effective way. [ABSTRACT FROM AUTHOR]

Very recently, half-hydrogenated germanene has been achieved in an experiment. In this paper, we investigate the effects of tetracyanoquinodimethane (TCNQ) molecular adsorption and strain on the electronic properties of half-hydrogenated germanene through first-principles. As an electron-acceptor molecule, TCNQ is exploited to non-covalently functionalize the half-hydrogenated germanene. However, this physical adsorption induces a ferromagnetic semiconductor–metal transition in half-hydrogenated germanene due to charge transfer from the substrate to the TCNQ molecule. More importantly, the superstructure of half-hydrogenated germanene/TCNQ is extremely sensitive to biaxial tensile strain. Under the biaxial tensile strain of 0.25%, the ferromagnetic semiconductor–metal transition induced by molecular adsorption can surprisingly be overturned. Meanwhile, a strong p-type doping is exhibited. Remarkably, it would return from a ferromagnetic semiconductor to a metal again when the biaxial tensile strain increases to 1.5%. Our analysis based on the structural and electronic properties of half-hydrogenated germanene/TCNQ indicates that such metal–semiconductor–metal transition in half-hydrogenated germanene/TCNQ under biaxial tensile strain may originate from the strong local deformation, resulting in the energy of the valence band maximum decreasing below or increasing above the Fermi level. [ABSTRACT FROM AUTHOR]

Grain boundaries in two-dimensional (2D) semiconductors generally induce distorted band alignment and interfacial charge, which impair their electronic properties for device applications. Here, we report the improvement of band alignment at the grain boundaries of PtSe2, a 2D semiconductor, with selective adsorption of a presentative organic acceptor, tetracyanoquinodimethane (TCNQ). TCNQ molecules show selective adsorption at the PtSe2 grain boundary with strong interfacial charge. The adsorption of TCNQ distinctly improves the band alignment at the PtSe2 grain boundaries. With the charge transfer between the grain boundary and TCNQ, the local charge is inhibited, and the band bending at the grain boundary is suppressed, as revealed by the scanning tunneling microscopy and spectroscopy (STM/S) results. Our finding provides an effective method for the advancement of the band alignment at the grain boundary by functional molecules, improving the electronic properties of 2D semiconductors for their future applications. [ABSTRACT FROM AUTHOR]

We report the electronic absorption spectroscopy of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and its fluorinated derivatives (F2TCNQ and F4TCNQ), well-known electron-accepting molecules in common organic solvents (toluene, chlorobenzene, acetonitrile, and ethanol) under controlled exposure to air (O2) and UV light. All compounds (FxTCNQ (x = 0, 2, 4)) were stable in a neutral state (FxTCNQ0) in toluene and chlorobenzene, even under both O2 and UV light. On the other hand, in EtOH, the formation of FxTCNQ·− was monitored upon controlled exposure to O2 or UV light. Especially in air-equilibrated ethanol upon the UV-illumination, efficient α,α-dicyano-p-toluoylcyanide anion (DCTC−) and its fluorinated derivatives were generated evinced by the absorption peak near 480 nm, whereas the reaction was shut off by removing O2 or blocking UV light, thereby keeping FxTCNQ·− stable. However, even in deaerated ethanol, upon the UV-illumination, the anion formation of TCNQ and its fluorinated derivatives (FxTCNQ·−, x = 0, 2, 4) was inevitable, showing the stability of FxTCNQ0 depends on the choice of solvent. [ABSTRACT FROM AUTHOR]

A series of 1 : 1 cocrystals of weak donor–acceptor complexes between toluene and fluorinated derivatives of tetracyanoquinodimethane with alternating donor and acceptor components has been obtained. Mutual orientation of the donor and acceptor molecules in the stacks is similar to the geometry of supramolecular dimers corresponding to the energy minimum, according DFT simulation of the pairwise interactions. Thus, despite the fact that the energy of the π–π interactions has not exceeded 4 kcal/mol, they are highly important for the supramolecular organization of the donor and acceptor components in the cocrystals. Due to small size of the donor, the crystal packing is mainly determined by weak lateral interactions involving the acceptor molecules and is strongly dependent on the number of fluorine atoms. The charge transfer is estimated using the QTAIM method and does not exceed 0.06e. [ABSTRACT FROM AUTHOR]

Chemically altering molecules can have dramatic effects on the physical properties of a series of very similar molecular compounds. A good example of this is within the quasi-1D spin-Peierls system potassium TCNQ (TCNQ = 7,7,8,8-tetracyanoqunidimethane), where substitution of TCNQF4 for TCNQ has a dramatic effect on the 1D interactions, resulting in a drop in the corresponding spin-Peierls transition temperature. Within this work, we extend the investigation to potassium TCNQBr2, where only two protons of TCNQ can be substituted with bromine atoms due to steric constraints. The new system exhibits evidence for a residual component of the magnetism when probed via magnetic susceptibility measurements and muon spin spectroscopy. The observations suggest that the system is dominated by short range, and potentially disordered, correlations within the bulk phase.

This paper presents a novel macrocycle based on conformation‐adaptive and electron‐rich dihydrophenazine. The macrocycle exhibits host‐guest interaction with tetracyanoquinodimethane (TCNQ) driving by charge transfer interaction between them. The host‐guest complex forms stable radical cation species upon oxidation, resulting in the release of TCNQ from the macrocyclic cavity, thereby successfully achieving the reversible binding of guest molecules. More details are discussed in the article by Yang et al. on page 1895—1900. [ABSTRACT FROM AUTHOR]

The resonance interaction of ionizing electrons with 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules was studied by negative-ion mass spectrometry. The installation of an energy filter in the ion source confirmed the possibility of a dissociation process on the surface of the ionization chamber of the ion source. The formation of negative fragment ions through a dissociation channel based on the Schottky effect was demonstrated. [ABSTRACT FROM AUTHOR]

Transition metal nitrides have attracted great interest among the non‐noble catalysts employed in heterogeneous catalytic processes because of their exceptional stability and catalytic potential. However, the approach for their synthesis has remained a tremendous challenge. This study presents the synthesis of Co4N/C catalyst fabricated at 400, 600, and 800 °, symbolized as Co4N/C‐400, Co4N/C‐600, Co4N/C‐800, respectively. The characterization of fabricated catalysts is carried out through various advanced analytical techniques. As prepared nano‐catalyst Co4N/C shows remarkable catalytic efficiency in terms of low activation energy (Ea=3.038×10−1 KJ mol−1), fast conversion rate (Kapp=0.2884 s−1), and 97.57% conversion efficiency. Moreover, it also exhibits excellent stability and reusability because of its metallic characteristics. The outstanding catalytic activity of the catalyst is the combined effect in which the Co4N nanoparticles acted as active sites, and the carbon support doped with nitrogen provided an expressway for the transport of electrons required for catalytic reduction. Moreover, the designed catalyst is immobilized on the cellulose membrane filter support, to demonstrate the catalytic reduction of 4‐nitrophenol to 4‐aminophenol. We envision that our work would facilitate the fabrication of cobalt nitrides‐based nano‐catalysts for a wide range of industrial applications. [ABSTRACT FROM AUTHOR]

The dissociation of negative molecular ions of tetracyanoquinodimethane (TCNQ) on the surface of the ionization chamber of the ion source of a mass spectrometer modified for operation in the mode of resonant electron capture by molecules is studied. Based on the helium-puffing experiment and calculations by the B3LYP/6-31G method, it is shown that, under the influence of the induced charge, TCNQ– ions on the surface can dissociate through channels which is not possible in the gas phase due to lack of energy. The result is significant for improving the experiment on the resonant capture of electrons by molecules and solving the well-known problem of the destruction of materials based on TCNQ in electronic devices. [ABSTRACT FROM AUTHOR]

We present electronic properties of a charge transfer material consisting of Manganese(II)Phthalocyanine (MnPc) and 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), investigated by means of photoemission spectroscopy and electron energy-loss spectroscopy, as well as supporting density functional theory calculations. We report the successful formation of a bulk material characterized by a strong interaction of the molecular compounds which affects the optical properties significantly. Our investigations reveal a significant charge transfer, whereas the MnPc molecule is oxidized and F4TCNQ is reduced. The valence band data indicate a full charge transfer between the two partners. The electronic excitation spectrum reveals a relatively small energy gap of MnPc/F4TCNQ of about 0.7 eV, which is related to a charge transfer excitation. [ABSTRACT FROM AUTHOR]

Interfacial effects like orbital hybridization and charge transfer strongly influence the transfer of spins from ferromagnetic metals to organic semiconductors and can lead to the formation of interfacial states with distinct magnetic properties. The changes in the electronic and magnetic properties of a thin Co film upon adsorption of a layer of either the molecular organic electron donor tetrathiafulvalene (TTF) or the acceptor tetracyanoquinodimethane (TCNQ) have been investigated by X-ray absorption spectroscopy and X-ray magnetic circular dichroism using synchrotron radiation. Clear differences between the spectra of the adsorbed molecules and the neutral molecules show the hybridization of the molecular orbitals with the Co interface. Deposition of both organic materials leads to a small increase of the ratio of the orbital magnetic moment to the spin magnetic moment of the Co atoms at the interface. The main effect of overlayer deposition is a modification of the magnetic hysteresis of the Co film: The TCNQ slightly reduces the coercivity of the Co, while the TTF increases the coercivity by a factor of ~1.5. These complementary effects of either a molecular organic electron donor or acceptor on the interfacial properties of a metal ferromagnetic thin film are a promising result for the controlled modification of the magnetic structure of hybrid interfaces. [ABSTRACT FROM AUTHOR]

Tetracyanoquinodimethane (TCNQ) is widely used as an electron acceptor to form highly conducting organic charge-transfer solids. Surprisingly, the electron affinity (EA) of TCNQ is not well known and has never been directly measured. Here, we report vibrationally resolved photoelectron spectroscopy (PES) of the TCNQ- anion produced using electrospray and cooled in a cryogenic ion trap. Photoelectron spectrum taken at 354.7 nm represents the detachment transition from the ground state of TCNQ- to that of neutral TCNQ with a short vibrational progression. The EA of TCNQ is measured accurately to be 3.383 ± 0.001 eV (27 289 ± 8 cm-1), compared to the 2.8 ± 0.1 eV value known in the literature and measured previously using collisional ionization technique. In addition, six vibrational peaks are observed in the photoelectron spectrum, yielding vibrational frequencies for three totally symmetric modes of TCNQ. Two-photon PES via a bound electronic excited state of TCNQ- at 3.100 eV yields a broad low kinetic energy peak due to fast internal conversion to vibrationally excited levels of the anion ground electronic state. The high EA measured for TCNQ underlies its ability as a good electron acceptor. [ABSTRACT FROM AUTHOR]

Charge-transfer (CT) crystals bearing segregated domains between the electron donor and acceptor molecules are a promising platform for developing new organic functional solid-state materials. However, there is limited diversity in the segregated structures of CT crystals. Herein, we report a novel structure of a CT crystal using hexaarylbenzene (HAB) and tetracyanoquinodimethane (TCNQ) as the electron donors and acceptors, respectively. Single-crystal X-ray diffraction (XRD) studies revealed that hexapyridylbenzene and TCNQ form a segregated layer in crystalline media, and the CT feature of TCNQ was observed in terms of the observed chemical bond lengths in the crystal. [ABSTRACT FROM AUTHOR]

We use ab initio simulations to investigate the adsorption and the self-assembly processes of tetracyanoquinodimethane (TCNQ), tetrafluoro-tetracyanoquinodimethane (F4-TCNQ), and tetrasodium 1,3,6,8-pyrenetetrasulfonic acid (TPA) on the graphene surface. We find that there are no chemical bonds at the molecule-graphene interface, even at the presence of grain boundaries on the graphene surface. The molecules bond to graphene through van der Waals interactions. In addition to the molecule-graphene interaction, we performed a detailed study of the role played by the (lateral) molecule-molecule interaction in the formation of the, experimentally verified, self-assembled layers of TCNQ and TPA on graphene. Regarding the electronic properties, we calculate the electronic charge transfer from the graphene sheet to the TCNQ and F4-TCNQ molecules, leading to a p-doping of graphene. Meanwhile, such charge transfer is reduced by an order of magnitude for TPA molecules on graphene. In this case, it is not expected a significant doping process upon the formation of self-assembled layer of TPA molecules on the graphene sheet. [ABSTRACT FROM AUTHOR]

An approach for the lower rim modification of the calix[4]arene‐based molecular tweezes with monopyrrolo‐tetrathiafulvalene (MPTTF) arms attached to the upper rim of calixarenes is described. First, calixarene‐MPTTF conjugates with free hydroxyl on the lower rim are synthesized using the Ullmann reaction, then hydroxyl groups are substituted by propargyl groups, which can be used for further modification by the click reaction. The new calixarene‐TTF derivatives displayed reversible redox processes, as well as demonstrated binding affinity for electron‐deficient molecular guests such as tetracyanoquinodimethane. The described synthetic approach will be used for the modular synthesis of molecular receptors tailored for specific applications. [ABSTRACT FROM AUTHOR]

Tetracyanoquinodimethane (TCNQ) is known to react with primary/secondary amines to generate mono/di‐substituted TCNQ derivatives resulting in optical (fluorescence) and non‐linear optical characteristics. However, the choice of amine plays a key role in the sequel of certain material attributes. Nevertheless, demonstration of TCNQ derivatives, specifically obtained by reacting TCNQ with simple & small amine side chains of existing anticancer drugs, emerging in dual effect of fluorescence as well as anticancer activity, is not explored so far and has been still existing as a gap in TCNQ related research. Additionally, mono/di‐substituted TCNQ's owning strong fluorescence in solutions (∼10 to 104 order) than their solids are still lacking and are in need to be generated. In this regard, we aimed to synthesize straightforward TCNQ derivatives in single step by reacting TCNQ with specific (simple and small) amines being side chains of existing anticancer drugs (a contemporary design approach) and successfully obtained novel mono/di‐substituted TCNQ derivatives manifesting dual effect of fluorescence and anticancer activity. In this fashion, we have avoided the usage of bulky main moiety of an anticancer molecule, since our aim was not to use the total anticancer drug as such, like in a Pro‐drug preparation, but we intended to use the minimal part of an anticancer drug to invent novel TCNQ derivatives as anticancer active fluorophores. Wavelength of maximum emission for all the five potent molecules was within ∼525 nm‐696 nm. All compounds showed moderate anticancer activity against different cancer cell lines and IC50 values were in the range of 11 to 49 μM, when the synthesized novel compounds were tested in B16F10, MDA‐MB‐231 and A549 cell lines. Henceforth, this study has emanated in the first generation TCNQ derivatives as organic fluorescent anticancer active molecules. [ABSTRACT FROM AUTHOR]

The interface between the tetrathiafulvalene/tetracyanoquinodimethane (TTF-TCNQ) organic blend and the Au(111) metal surface is analyzed by Density Functional Theory calculations, including the effect of the charging energies on the molecule transport gaps. Given the strong donor and acceptor characters of the TTF and TCNQ molecules, respectively, there is a strong intermolecular interaction, with a relatively high charge transfer between the two organic materials, and between the organic layer and the metal surface. We find that the TCNQ LUMO peak is very close to the Fermi level; due to the interaction with the metal surface, the organic molecular levels are broadened, creating an important induced density of interface states (IDIS). We show that the interface energy level alignment is controlled by the charge transfer between TTF, TCNQ, and Au, and by the molecular dipoles created in the molecules because of their deformations when adsorbed on Au(111). A generalization of the Unified-IDIS model, to explain how the interface energy levels alignment is achieved for the case of this blended donor/acceptor organic layer, is presented by introducing matrix equations associated with the Charge Neutrality Levels of both organic materials and with their intermixed screening properties. [ABSTRACT FROM AUTHOR]

In this paper, the fabrication and characterization of CH3NH3PbI3 perovskite solar cells using decaphenylpentacyclosilane, copper phthalocyanine complex (CuPc) doped with tetracyanoquinodimethane (TCNQ), was performed. The effects of a carboxylic acid, amino, or sulfonic acid sodium salt group, substituted with CuPc doped with TCNQ, on photovoltaic properties was investigated to improve carrier generation and diffusion related to short-circuit current density. The incorporation of carboxylic acid or amino, substituted with CuPc doped with TCNQ, would optimize the tuning energy levels of the valence band, promoting charge transfer and diffusion with a suppressing trap near the interface in the hole-transporting layer.

In organic device applications, a high contact resistance between metal electrodes and organic semiconductors prevents an efficient charge injection and extraction, which fundamentally limits the device performance. Recently, various contact doping methods have been reported as an effective way to resolve the contact resistance problem. However, the contact doping has not been explored extensively in organic field effect transistors (OFETs) due to dopant diffusion problem, which significantly degrades the device stability by damaging the ON/OFF switching performance. Here, the stability of a contact doping method is improved by incorporating "dopant‐blockade molecules" in the poly(2,5‐bis(3‐hexadecylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT) film in order to suppress the diffusion of the dopant molecules. By carefully selecting the dopant‐blockade molecules for effectively blocking the dopant diffusion paths, the ON/OFF ratio of PBTTT OFETs can be maintained over 2 months. This work will maximize the potential of OFETs by employing the contact doping method as a promising route toward resolving the contact resistance problem. [ABSTRACT FROM AUTHOR]

Flexible, light-weight and robust thermoelectric (TE) materials have attracted much attention to convert waste heat from low-grade heat sources, such as human body, to electricity. Carbon nanotube (CNT) yarn is one of the potential TE materials owing to its narrow band-gap energy, high charge carrier mobility, and excellent mechanical property, which is conducive for flexible and wearable devices. Herein, we propose a way to improve the power factor of CNT yarns fabricated from few-walled carbon nanotubes (FWCNTs) by two-step method; Joule-annealing in the vacuum followed by doping with p-type dopants, 2,3,5,6-tetrafluo-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Numerical calculations and experimental results explain that Joule-annealing and doping modulate the electronic states (Fermi energy level) of FWCNTs, resulting in extremely large thermoelectric power factor of 2250 µW m−1 K−2 at a measurement temperature of 423 K. Joule-annealing removes amorphous carbon on the surface of the CNT yarn, which facilitates doping in the subsequent step, and leads to higher Seebeck coefficient due to the transformation from (semi) metallic to semiconductor behavior. Doping also significantly increases the electrical conductivity due to the effective charge transfers between CNT yarn and F4TCNQ upon the removal of amorphous carbon after Joule-annealing. [ABSTRACT FROM AUTHOR]

Atomically thin two dimensional materials such as graphene offer excellent capabilities suitable for a number of low power versatile applications. Here, employing first principle calculations, we introduce a feasible approach to realize an efficient graphene based p-n junction (PNJ) which is composed of non-covalently physisorbed tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) molecules onto an armchair graphene nanoribbon (AGNR). We show that compared to conventional graphene based p-n systems, our suggested PNJ exhibits low threshold voltage ( V t h ), large current-voltage ratio, and almost no sensitivity to conformational variations. Using a simple model, we also provide a theoretical background to explain the rectifying behavior of the suggested PNJ and show that tuning the distance between p and n doped regions modifies the current-voltage ratio. Our study indicates that the perfect diode behavior along with stability under various practical conditions makes our proposed PNJ a promising building block to fabricate next generation graphene based nanosize transistors. Image 1 [ABSTRACT FROM AUTHOR]

Various nanoparticle surface layers allow unique functionalities. We developed a coating method with tetracyanoquinodimethane that forms solid layers through π stacking on gold nanorod surfaces. Its reaction mechanism was investigated with reaction time, aging time and surfactant concentration. Our method could be generalizable to different nanoparticle shapes and crystal facets. [ABSTRACT FROM AUTHOR]

Samples of polyaniline synthesized from aniline sulfate were electrochemically cycled in LiCl, LiClO4, and lithium tetracyanoquinodimethane, with the electrolyte replacement. In all studied cases, the polyaniline is shown to retain its electrochemical activity upon the electrolyte and doping anion replacement. The electrochemical activity with the Cl– and dopants is reduced in the first cycles upon the electrolyte replacement; however, in the subsequent cycles the reduction decreased. When the electrode under testing has been returned to the native electrolyte, its electrochemical activity and electrochemical capacitance increased, recovering their initial values. When polyaniline has been doped with the tetracyanoquinodimethane anion, each next cycling series revealed an increase in its electrochemical activity, which manifests itself in the cyclic voltammogram area, as well as increase in the electrochemical capacitance from one cycling series to the next one. [ABSTRACT FROM AUTHOR]

In this study, we performed a micro/nanocrystallization of charge transfer crystals (CTCs) composed of tetrathiafulvalene (TTF)-- tetracyanoquinodimethane (TCNQ) via a charge transfer-induced reprecipitationmethod. Depending on the order of injected solution, TTF--TCNQ CTCs formed a nanorod or a nanorod-coated rhombic shape.We concluded that the crystallinity of the TCNQ particles in the water dispersion determines the final CTC shape. [ABSTRACT FROM AUTHOR]

Possible adsorption configurations and electronic properties, such as charge analysis, density of states, work function and Schottky barrier height of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) on Aluminium (100) surface is studied by using density functional theory methods with local density approximation (LDA), generalised gradient approximation (GGA), PBE and PBE-D2 methods. TCNQ is strongly adsorbed on Al(100) with adsorption energy of −3.66 eV. The charge is transferred from Al(100) to TCNQ and charge transfer occurs mainly through cyano group of TCNQ. Adsorption on Al(100) surface leads to downshift in energy difference between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of TCNQ by 2.5 eV as result of hybridisation of p orbital of carbon and nitrogen atoms of TCNQ and p orbital of surface Al atoms. Compared to TCNQ adsorption, TTF adsorption on Al(100) surface is having less adsorption energy and type of interaction is physisorption. The charge transfer from TTF to Al(100) surface leads to decrease in work function of Al by 0.24 eV. The n-type Schottky barrier height of TCNQ/Al(100) and p-type Schottky barrier height of TTF/Al(100) is 0.68eV and 1.97 eV, respectively showing that TCNQ and Al(100) are suitable for organic photovoltaic and electrochemical applications. [ABSTRACT FROM AUTHOR]

In this study, the nature and characteristics of the intramolecular and intermolecular interactions in crystal structures of the fluoro‐substituted 7,7,8,8‐tetracyanoquinodimethane (TCNQ) family of molecules, i.e. Fx‐TCNQ (x = 0, 2, 4), are explored. The molecular geometry of the reported crystal structures is directly dependent on the degree of fluorination in the molecule, which consequently also results in the presence of an intramolecular N[triple‐bond]C...F—C π‐hole tetrel bond. Apart from this, the energy framework analysis performed along the respective transport planes provides new insights into the energetic distribution in this class of molecules. Charge density and energy framework analysis provide quantitative insights into the relevance of intermolecular interactions and transport properties in the fluoro‐substituted TCNQ family of molecules. [ABSTRACT FROM AUTHOR]

The mass spectrum of negative ions due to resonance electron capture by molecules of tetracyanoquinodimethane (TCNQ), a well-known electron acceptor, has been recorded in order to identify the dissociation processes of TCNQ molecular negative ions on the surface of an ionization chamber at thermal energies of electrons to be attached to the molecules. It has been found that the TCNQ molecular negative ions, preliminarily generated in the gas phase at several resonance maxima, reach the ionization chamber walls owing to a long extra-electron autodetachment lifetime ranging from 25 s in the first resonance at zero electron energy to 0.2 s in the resonance at 3.3 eV and dissociate at the walls as a result of the influence of the surface on the energy balance of the dissociation process. It has been taken into account that without the surface effect on the energy balance, this dissociation would be impossible because of an insufficient energy of the electron captured by the molecule. By B3LYP/6-311G calculations, the most probable dissociation pathways have been determined for negative fragment ions with various empirical formulas. The data obtained can be used to solve problems related to the properties of the TCNQ molecule in interaction with the conductive surface of a metal substrate in electronic devices. [ABSTRACT FROM AUTHOR]

Highlights • One layer of TCNQ accepts electrons from MoS 2 surface • MoS 2 bands are shifted rigidly by charge transfer to TCNQ • Rigid band shifts can control optoelectronic properties without altering details of band structure Abstract Adsorption of the acceptor material tetracyanoquinodimethane can control optoelectronic properties of MoS 2 by accepting defect generated excess negative charge from the surface that would otherwise interfere with radiative decay processes. Angle Resolved Photoelectron Spectroscopy measurements show that the MoS 2 band structure near the Γ point shifts rigidly upward by ∼0.2 eV for a complete surface coverage of acceptor species as expected for an upward Fermi level shift due to charge transfer to the TCNQ. The molecular adsorbate orbitals visible in photoemission are indicative of an anionic species, consistent with interfacial charge transfer but without evidence for hybrid states arising from covalent adsorbate-surface interactions. Thus, our interface studies support the notion that molecular adsorbates are a useful tool for controlling optoelectronic functionality in 2D materials without fundamentally modifying their favorable band structures. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Tetrathiafulvalene (TTF) has been one of the most studied compounds, since the discovery of electrical conductivity as a charge‐transfer complex in combination with tetracyano‐p‐quinodimethane (TCNQ) in 1973. In 2004, TTF was realized in a new light as an innate semiconductor material, as well as conductor and superconductor material. Because of the ready modification of its core skeleton and better solubility than that of acene compounds, many TTF derivatives have been reported to attain better charge‐carrier mobility for field‐effect transistor devices. Considering the high charge‐carrier mobility of acene and TTF derivatives, annulation of the acene and TTF moieties is expected to improve the charge‐carrier mobilities. This Minireview focuses on the syntheses, crystal structures, and electronic properties of state‐of‐the‐art π‐extended TTF derivatives, based on the history of the development of TTF derivatives. The relationship between the packing structure and charge‐carrier mobilities is also discussed. Expanding the range: New tetrathiafulvalene compounds annulated with acenes, electron‐withdrawing imides, quinozalines, benzothiadiazole, and imides (see figure) are reviewed as organic semiconducting materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The study uses SWV to determine N-hydroxycytidine (NHC) and verapamil (VER) levels in plasma samples. • The SWV method with CuTCNQ-modified CPE has potential to detect NHC and VER simultaneously. • The sensor was characterized using spectroscopic and electrochemical techniques. • The method successfully analyzed real rabbit plasma samples with high sensitivity and selectivity. • Pharmacokinetic parameters were calculated for NHC with and without VER co-administration. This study focuses on the determination of the active metabolite of molnupiravir (MOL), N-hydroxycytidine (NHC), using a square wave voltammetric (SWV) method. Carboxylesterase-2 enzymes catalyze the conversion of MOL prodrug into NHC. However, co-administration of verapamil (VER), a carboxylesterase-2 inhibitor, may reduce the levels of NHC, leading to decreasing its antiviral activity. In this context, the levels of NHC and VER were simultaneously monitored using a carbon paste electrode modified with phase I of copper tetracyanoquinodimethane (CuTCNQ) which is highly conductive charge transfer complex. The as-designed sensor was characterized successfully using various spectroscopic techniques and Scanning Electron Microscopy (SEM). The electrochemical behavior of the newly fabricated probe was examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). This method demonstrated its efficacy in measuring NHC and VER levels in rabbit plasma samples, showing high sensitivity and selectivity. The calibration plots for the simultaneous quantitation of NHC and VER displayed excellent linearity over the concentration ranges of 50–1600 nmol/L for NHC and 10–250 nmol/L for VER. The limits of detection (LOD) and quantitation (LOQ) in rabbit plasma were found to be 15.2 and 50.8 nmol/L for NHC and 2.9 and 9.9 nmol/L for VER, respectively. Moreover, fundamental pharmacokinetic parameters were calculated for NHC before and after co-administration of VER. The results suggest that the SWV method using CuTCNQ-modified CPE can be a useful tool for the determination of NHC and VER levels in plasma samples, with potential applications in the monitoring of drug-drug interactions involving carboxylesterase-2 inhibitors. [ABSTRACT FROM AUTHOR]