Search

Benzothienobenzothiophenes (BTBTs) are a class of heteroacenes for which two distinct isomers have been identified depending on the locations of the fused benzothiophene motifs. Benzothienobenzothiophenes represent a class of heteroacenes demonstrating remarkable electronic properties that make them prominent in the realm of organic semiconductors. The structure of BTBTs, incorporating two sulfur atoms, contributes to their unique electronic characteristics, including narrow bandgaps and effective charge transport pathways. These compounds have gained attention for their high charge carrier mobility, making them desirable candidates for application in organic field‐effect transistors (OFETs) and other electronic devices. Researchers have explored various synthetic strategies to design and tailor the properties of BTBT derivatives, leading to advancements in the development of high‐performance organic semiconductors. Various synthetic techniques for benzothienobenzothiophenes have been reported in the literature including multistep synthesis, tandem transformations, electrochemical synthesis, and annulations. This review investigates the generality of each synthetic methodology by highlighting its benefits and drawbacks, and it analyses all synthetic approaches described for the creation of the two isomers. For the advantage of the readers, we have delved upon every mechanism of the reactions that are known. Finally, we have also summarized the synthetic methodologies that are used for making benzothienobenzothiophene analogues for material applications. [ABSTRACT FROM AUTHOR]

Cs2AgBiBr6 double perovskite compounds are increasingly studied in recent years as promising candidates able to counter polluting, harmful, and oxygen‐/moisture‐sensitive issues intrinsic to traditional lead‐containing solar cells. Exhibiting high optical absorption coefficient, low toxicity, and important structural stability, Cs2AgBiBr6 solar cells still suffer from limited absorption of low‐energy photons, low carrier mobility, and limited carrier lifetimes induced by defect states. Herein, for the first time, a molecular layer of tetracene is introduced within a Cs2AgBiBr6‐based photovoltaic architecture: being incorporated at the interface between the double perovskite photoabsorber and spiro‐OMeTAD hole transport material, tetracene allows for a suitably graded cascade of energy bands within the solar cell architecture, which ultimately improves interfacial charge transfers and reduces charge recombination. The performances in photovoltaic devices are consequently enhanced versus tetracene‐free configurations, with champion values of open‐circuit voltages of 1.1 V (vs. 1.0 V), current densities of 2.5 mA cm−2 (vs. 1.9 mA cm−2), and photoconversion efficiencies of 1.7% (vs. 1.3%) with reduced hysteretic behavior. [ABSTRACT FROM AUTHOR]

The synthesis of multiply substituted acenes is still a relevant research problem, considering their applications and future potential. Here we present an elegant synthetic protocol to afford tetra-peri-substituted naphthalene and tetracene from their tetrahalo derivatives by a Pd(0)-catalyzed C-C cross-coupling method in a single step. The newly synthesized tetracenes were characterized by NMR, HRMS, UV-vis spectrophotometry, and single-crystal X-ray diffraction (SCXRD). In addition, the first systematic computational study of the effect of chalcogenophenyl substitutions on the chiroptical properties of twistacenes was reported here. The gas phase computational studies using density functional theory (DFT) on a series of chalcogenophene-substituted tetracenes revealed that their chiroptical activity could be systematically increased via the atomistic tuning of peripheral substituents. [ABSTRACT FROM AUTHOR]

Context: This study aims to tune the transport properties of tetracene single-molecule junctions with the proper choice and placement of side and anchoring groups. For the operationalization of the molecule that was anchored with thiol or isocyanide groups, two different side groups, amine and nitro, in two different positions, were taken into consideration. For unperturbed tetracene molecule, a prominent negative differential resistance (NDR) feature at 1.8 V was observed with the isocyanide anchoring group while the thiol anchoring group exhibits a plateau region over a bias voltage of 2.2 to 3.2 V. At a bias voltage that is dependent on the chemical or structural change of side or anchoring groups, NDR feature of varying degree was seen in all configurations. Results show that the current flowing through the thiol-anchored molecule perturbed with the amine group at S' position is relatively larger than other configurations because of the smaller HOMO-LUMO gap and broader transmission peaks resulting in a peak to valley current ratio (PVCR) of 1.22. In addition, multiple NDR regions were realized in nitro-perturbed isocyanide-anchored molecule at S position. These results suggest their promising applications in switches, logic cells, and storage devices. Methods: The modeling and simulation of side-group mediated anchored tetracene molecule through two electrodic systems were studied using density functional theory (DFT) combined with non-equilibrium Green's function (NEGF) in Virtual NanoLab-AtomistixToolkit (ATK). The electron transport properties were calculated using Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) exchange-correlation function. To optimize computing time, gold electrodes were single zeta polarized whereas the molecule, anchor groups, and side groups were double zeta polarized. [ABSTRACT FROM AUTHOR]

The geometric structures, vibrational frequencies and relative energies of all reactants, products, intermediates, and transition states involved in the self-recombination of the indenyl radical were determined using G3(MP2,CC) // B3LYP/6-311G** quantum chemical calculations. The barrierless association of a pair of indenyl radicals forms the C18H14 complex. The subsequent set of isomerizations of the complex is divided into five reaction channels, which in all cases end in H abstraction with different four-ring isomers C18H14: in the form of condensed rings (tetraphene, tetracene, chrysene, and dibenzoazulene) and with an associated internal bond of the rings (dibenzofulvalene). The yield of chrysene prevails since the energy barriers for its formation are lower than those for the formation of other products. [ABSTRACT FROM AUTHOR]

The perovskite solar cell has recently gained momentum within the renewable energy industry due to its unique advantages such as high efficiency and cost-effectiveness. However, its instability remains a challenge to its commercialization. In this study, a singlet fission material, namely tetracene, is coupled with the perovskite solar cell to simulate its effect on the solar cell. The amount of thermalization loss and the temperature of the perovskite layer are simulated and analyzed to indicate the mechanism's effectiveness. We found that coupling the tetracene layer resulted in a drastic reduction in thermalization loss and a slower slope in perovskite layer temperature. This indicates that tetracene would stabilize the perovskite solar cell and minimize its potential losses. The thickness of the solar cell layers is also analyzed as a factor of the overall effectiveness of singlet fission on solar cells. [ABSTRACT FROM AUTHOR]

Singlet excitons fission (SF) into triplet excitons can enhance the efficiency of solar cells while reducing the heat loss in light absorption systems, but requires photostable materials with high triplet yield. We use Support Vector Regression (SVR) to establish a Quantitative Structure-Property Relationship (QSPR) model for perdition the triplet yield (ΦSF) of singlet fission materials (tetracene, pentacene, and perylenedimide derivatives, etc.). Minimum redundancy maximum relevance (mRMR), Floating front search (FFS) and Grid-search were used to select property molecular descriptions and parameter optimization, then the SVR model was established to predict the ΦSF of these compounds. The correlation coefficient R values of leave one out cross-validation (LOOCV) test and external validation test set were 0.88 and 0.93, respectively. The results show that the SVR-QSPR model has strong generalization ability, can predict the ΦSF value of singlet fission materials effectively and guide significance for developing highly efficient solar cells.

We newly synthesized a series of homo‐ and hetero‐tetracene (Tc) oligomers to propose a molecular design strategy for the efficient exciton transport in linear oligomers by promoting correlated triplet pair (TT) dissociation and controlling sequential exciton trapping process of individual doubled triplet excitons (T+T) by intramolecular singlet fission. First, entropic gain effects on the number of Tc units are examined by comparing Tc‐homo‐oligomers [(Tc)n: n=2, 4, 6]. Then, a comparison of (Tc)n and Tc‐hetero‐oligomer [TcF3‐(Tc)4‐TcF3] reveals the vibronic coupling effect for entropic gain. Observed entropic effects on the T+T formation indicated that the exciton migration is rationalized by number of possible TT states increased both by increasing the number of Tc units and by the vibronic levels at the terminal TcF3 units. Finally, we successfully observed high‐yield exciton trapping process (trapped triplet yield: ΦTrT=176 %). [ABSTRACT FROM AUTHOR]

[Display omitted] • Tetracene-based chromophores are investigated for solvent and frequency-dependent NLO properties. • DFT and TDDFT analyses include NBO, UV–Vis, FMO, and topological (MEP, ELF, LOL) studies. • Chromophores ZO-9 show β total values ranging from 1.993 × 105 (gas) to 1.180 × 106 (water). • Significant SHG and EOPE values are observed at 532 nm and 1064 nm laser wavelengths. • Chromophores are recommended for advanced electro-optic and switching applications. Tetracene-based nonlinear optical (NLO) materials are an ambient field of interest in optoelectronic technology. Inspired by this material, we theoretically designed D-D-A framework molecules (ZO and ZO-1 to ZO-16) with auxiliary donor and acceptor screening of solo tetracene linear surface and investigated their reactivity, electrical properties, solvent-dependent optical and ON/OFF NLO properties utilizing DFT simulations. The CPCM and IEFPCM model is used to examine how entire spectrum of medium polarity, ranging from less polar to more polar solvents (chloroform (ε = 4.71) < tetrahydrofuran (ε = 7.43) < DMSO (ε = 46.83 < water (ε = 78.36)) affect the optical absorption and NLO characteristics (β tot , α tot , and μ tot) of suggested compounds (ZO and ZO-1 to ZO-16). Furthermore, natural bond orbital analysis (NBO) and topological analysis (MEP, ELF, and LOL) were used to explain the NLO results. Regarding the charge transfer robustness, ZO-9, a promising tetracene derivative, is identified as an appealing second-order NLO candidate, with the lowest energy gap (1.642 eV) and largest λ max (546.692 nm) among all investigated derivatives. Moreover, the solvent-dependent optical absorption spectrum shows that polar solvent (THF) alleviates the λ max from 273.081 nm to 707.511 nm in ZO-11. Similarly, solvent also influences the NLO properties in all designed compounds, especially in ZO-9, which displayed giant β total = 7.244 × 105 in chloroform, 8.640 × 105 in THF, 1.153 × 106 in DMSO, and 1.180 × 106 in water as well as in gas (1.993 × 105). Additionally, the results of the second harmonic generation (SHG) β(−2ω, ω, ω) and the electro-optical Pockels effect (EOPE) β(−ω,ω,0) computed at the frequencies of ω = 1064 nm (0.0428 au) and ω = 532 nm (0.0856 au) validates that all tetracene based derivatives are excellent NLO candidates for laser working condition and switching applications. [ABSTRACT FROM AUTHOR]

The electronic structure, dipole moment (µ), average polarizability (< α >), anisotropie (Δα), first molecular hyperpolarizability (βmol), molar refractivity (κ) , HOMO energy (EHOMO), LUMO energy (ELUMO), energy gap (Egap), ionization potential (IP), electron affinity (EA), electronegativity (ς) , chemical potential (δ) , chemical hardness (ϑ) , chemical softness (σ) , and electrophilicity index (ω) , , total electronic energy (E0), zero point vibrational energy (zpve), thermal energy (E), Molar heat capacity at constant volume (CV), entropy (S), total electronic energy without Zero point correction (E1), total electronic energy with Zero point correction (E2), total electronic energy with thermal Energies (E3), total electronic energy with Enthalpies (E4), total electronic energy with thermal free Energies (E5), Volume (V), average Electric field (E), Polarization density (P), electric susceptibility (χ), relative dielectric constant (ɛr), dielectric constant (ɛ), refractive index (ɳ) and displacement vector (D) of doped and undoped pentacene and petracene have been determined by using Restricted Hartree–Fock (RHF), and Density Functional Theory (DFT) methods (B3LYP, WB97XD and BPBE) with the cc-PVDZ basis set. The aim of this work is to research new materials that can have applications in the fields of linear and nonlinear optics, electronics and optoelectronics. The results obtained from B3LYP, WB97XD and BPBE level show that the molecules are good semiconductor with very good optoelectronic properties and may have application in photonic, electronic, optoelectronics, organic light-emitting diode (OLEDs) and thin films. The large values of the refractive index (ɳ) and electric susceptibility (χ) of these molecules allow us to conclude that these molecules have good linear and nonlinear optical, electronic optoelectronic and photonic applications. [ABSTRACT FROM AUTHOR]

The synthesis of multiply substituted acenes is still a relevant research problem, considering their applications and future potential. Here we present an elegant synthetic protocol to afford tetra-peri-substituted naphthalene and tetracene from their tetrahalo derivatives by a Pd(0)-catalyzed C-C cross-coupling method in a single step. The newly synthesized tetracenes were characterized by NMR, HRMS, UV-vis spectrophotometry, and single-crystal X-ray diffraction (SCXRD). In addition, the first systematic computational study of the effect of chalcogenophenyl substitutions on the chiroptical properties of twistacenes was reported here. The gas phase computational studies using density functional theory (DFT) on a series of chalcogenophene-substituted tetracenes revealed that their chiroptical activity could be systematically increased via the atomistic tuning of peripheral substituents.

The perovskite solar cell has recently gained momentum within the renewable energy industry due to its unique advantages such as high efficiency and cost-effectiveness. However, its instability remains a challenge to its commercialization. In this study, a singlet fission material, namely tetracene, is coupled with the perovskite solar cell to simulate its effect on the solar cell. The amount of thermalization loss and the temperature of the perovskite layer are simulated and analyzed to indicate the mechanism’s effectiveness. We found that coupling the tetracene layer resulted in a drastic reduction in thermalization loss and a slower slope in perovskite layer temperature. This indicates that tetracene would stabilize the perovskite solar cell and minimize its potential losses. The thickness of the solar cell layers is also analyzed as a factor of the overall effectiveness of singlet fission on solar cells.

The syntheses of ethano-tetracyclic tetracenes; 14-cyano-5,12-dihydro-5,12-ethanotetracen-14-yl acetate (2a and 2b) and 5,12-dihydro-5,12-ethanotetracen-13-one (3) are reported. The tetracenes isomers 2a and 2b are equally obtained via DA reaction and the tetracene 3 is synthesized from the alkaline hydrolysis of 2a and 2b. The DFT calculations of tetracenes isomers 2a and 2b are performed and gave good agreement to the experimental result. The structure of tetracene 3 is elucidated by X-ray technique and its intermolecular interactions are determined by Hirshfeld surface analysis. The crystal system of tetracene 3 is orthorhombic with a Pca21 space group; a = 28.589 (5) Å, b = 6.5023 (14) Å, c = 7.5101 (11) Å, V = 1396.1 (4) Å3, Z = 4. This is the first report describing syntheses Ethano-tetracyclic tetracenes 2a, 2b, 3. DFT studies were used to explain the reaction regioselectivity of the two tetracene isomers 2a, 2b. The x-ray is performed to elucidate the structure of tetracene 3. Hirshfeld surface analysis is performed to determine the intermolecular interactions in the crystal structure of the tetracene 3. [ABSTRACT FROM AUTHOR]

Multifunctional operation of tetracene/polycyclopentadithiophene‐benzothiadiazole (PCPDTBT), and tetracene sensitized PCPDTBT:fullerene bulk heterojunctions (BHJs) that work as an organic photovoltaic (OPV), organic light emitting diode (OLED), and organic photodetector (OPD) is unveiled. The multifunctional operation is underlined by a synergetic interplay between singlet and triplet energy transfer and the judicious alignment of energy levels of donor–acceptor cascade. Introduction of tetracene is shown to enhance electroluminescence (EL) at 800 nm despite the observation of a near‐complete photoluminescence quenching in BHJ systems. Signatures of triple energy transfer mediated via charge transfer states of BHJ to tetracene become apparent as the proportion of fullerene in the BHJ is increased. An optimal balance between exciton population is achieved with BHJ 1:2 that produces EL peaks at 530 and 800 nm while maintaining a respectable OPV and OPD performance. The proposed ternary system unlocks the potential of having multifunctionality within one single diode structure, and it also offers new design rules for multispectral OLEDs. [ABSTRACT FROM AUTHOR]

Singlet fission is a potential mechanism to enhance the performance of current solar cells. However, the actual mechanism is still a matter of debate, with charge transfer states believed to play an essential role. The probability of the overall process can be related to the electronic coupling between the electronic states. Here, we explore the excited states of three pairs of tetracene with different relative orientation in the crystal structure showing different electronic couplings and identify the role of charge transfer states. First, a suitable theoretical method for the study of the tetracene pairs is determined by comparing time-dependent density functional theory with wave function-based methods in terms of excitation energies, so-called exciton descriptors, and graphical tools such as electron-hole correlation plots and natural transition orbitals. The results show the presence of low-lying charge transfer states in those tetracene pairs with non-zero electronic coupling, suggesting a superexchange-mediated mechanism, and high-lying charge resonance states for the pair with zero electronic coupling. Finally, the lower electron-hole correlation coefficients for pairs with non-zero coupling speak in favour of the superexchange-mediated mechanism, as a weaker Coulombic attraction due to the mixing with charge transfer states further facilitates the formation of the 1 T T state from the photoexcited molecule. [ABSTRACT FROM AUTHOR]

Singlet fission has emerged as a promising strategy to avoid the loss of extra energy through thermalization in solar cells. A family of dimers consisting of nitrogen‐doped pyrene‐fused acenes that undergo singlet fission with triplet quantum yields as high as 125 % are presented. They provide new perspectives for nitrogenated polycyclic aromatic hydrocarbons and for the design of new materials for singlet fission. [ABSTRACT FROM AUTHOR]

An organic molecular single-electron transistor (SET) based on a tetracene quantum dot has been modeled and employed for sensing of chlorine gas, within the framework of density functional theory. The sensing behavior of the SET is estimated through a charge-stability diagram and total energy as a function of gate potential (TE vs. Vg) for varying distances of chlorine from the SET quantum dot, which could be used as an electronic fingerprint for detection. The better sensing ability, high power efficiency and large operational temperature range of tetracene SET, in comparison to conventional sensors, makes it a very powerful candidate for a chlorine gas sensor. [ABSTRACT FROM AUTHOR]

Using first-principles calculations we study the energetics of alkali metal (AM) atom intercalation into bulk tetracene crystals. We show that, contrary to the adsorption of Li and Na atoms on isolated tetracene molecules, the intercalation of these and other (K, Rb, Cs) AM atoms into bulk tetracene crystals is energetically favorable (with respect to forming an infinite AM crystal) in a wide range of AM concentrations and that the intercalation energy is noticeably lower than that for intercalation into graphite, a material used today in anodes of AM batteries. In case of Li, there is no swelling of the intercalated crystals, and for Na the increase in crystal volume is less than 10%, which makes crystalline tetracene attractive from the viewpoint of energy storage, as the capacity exceeds the theoretical capacity of graphite. We further assess diffusion barriers of AM atoms, which for Li and Na proved to be below 0.5 eV, indicating a high diffusivity of these atoms already at room temperature. We also study the effects of intercalation on the electronic properties of the system, and show that several bands can be filled upon intercalation, so that the system exhibits semiconducting–metallic–semiconducting behavior when AM atom concentration increases. Our results shed light on the perspective of using AM atom intercalation into tetracene crystals for energy storage and tuning the electronic properties of this system. [Display omitted] • Intercalation of alkali metal atoms into tetracene crystals is energetically favorable. • For of Li and Na, the swelling of the intercalated crystals is small. • The capacity exceeds the theoretical capacity of graphite. • Several electronic bands can be filled upon intercalation. [ABSTRACT FROM AUTHOR]

Self-assembled strategy has been proven to be a promising vista in constructing organized low-dimensional nanostructures with molecular precision and versatile functionalities on solid surfaces. Herein, we investigate by a combination of scanning tunneling microscopy (STM) and dispersion-corrected density functional theory (DFT), the adsorption of tetracene molecules on the silver substrate and the mechanism mediating the self-assembly on Ag(110). As expected, ordered domain is formed on Ag(110) after adsorption with adjacent molecules being imaged with alternating bright or dim pattern regularly. While such behavior has been assigned previously to the difference of molecular adsorption height, herein, it is possible to investigate essentially the mechanism leading to the periodic alternation of brightness and dimness for tetracene adsorbed on Ag(110) thanks to the consideration of Van der Waals (vdW) dispersion force. It is demonstrated that the adsorption height in fact is same for both bright and dim molecules, while the adsorption site and the corresponding interfacial charge transfer play an important role in the formation of such pattern. Our report reveals that vdW dispersion interaction is crucial to appropriately describe the adsorption of tetracene on the silver substrate, and the formation of delicate molecular architectures on metal surfaces might also offers a promising approach towards molecular electronics.

We investigate the magnetophotocurrent (MPC) response in tetracene-based diodes and attribute the initially decreasing and then increasing MPC responses to the feature of the singlet fission (SF) reaction (a magnetic field sensitive process) as modulated by the applied magnetic field in the tetracene active layer. The SF reaction is further characterized by the magnetophotoluminescence (MPL) measurement of the tetracene film, in which the variation of MPL is correlated with the change of MPC response in the device. However, the SF reaction of the singlet excitons in the tetracene would compete with the separation of the opposite charge carriers at the donor/acceptor interfaces by depositing the fullerene (C 60 ) on the tetracene active layer to yield a planar heterojunction. Our results indicate that the charge separation is more effective than the SF reaction. The dissociation and the charge reaction processes of the charge transfer complexes at donor/acceptor interfaces dominate the photocurrent as well as MPC response in tetracene/C 60 -based diodes. [ABSTRACT FROM AUTHOR]

A new derivate of tetracene (DTTA) was synthesized and characterized. From the UV spectrum, compound DTTA showed more stability than rubrene towards photo–oxidization in solid state. The increased stability of DTTA could be explained by the lower energy level of HOMO. Crystal structure is similar to that of rubrene, and based on the calculated results from the Pw91pw91/6-31 g software, good performance of DTTA is expected. [ABSTRACT FROM AUTHOR]

In this study, density functional theory calculations were carried through on semiconductor species based on anthracene and tetracene. In particular, the effects of functionalization by electron with-drawing groups (F, Cl, NO 2 , CN, and N) on the electronic properties of anthracene and tetracene were studied. According to the calculations, functionalizingby F, Cl, NO 2 , and N increases the reorganization energies (λ + and λ − )compared to those of CN-functionalized systems. On the other hand, the functionalization of anthracene and tetracene leads to an enhancement of the adiabatic electron affinities (EA) and the 1st ionization potential (IP) in addition to reducing the HOMO-LUMOenergy gap which implies that the resulting species will have lower kinetic stability and higher carrier mobility compared to unsubstituted anthracene and tetracene. [ABSTRACT FROM AUTHOR]

Seven longitudinally twisted acenes (an anthracene, two tetracenes, three pentacenes, and a hexacene) have been synthesized by the addition of aryllithium reagents to the appropriate quinone precursors, followed by SnCl2-mediated reduction of their diol intermediates, and several of these acenes have been crystallographically characterized. The new syntheses of the three previously reported twisted acenes, decaphenylanthracene ( 1), 9,10,11,20,21,22-hexaphenyltetrabenzo[ a, c, l, n]pentacene ( 2), and 9,10,11,12,13,14,15,16-octaphenyldibenzo[ a, c]tetracene ( 14), resulted in a reduction of the number of synthetic steps. As a consequence their overall yields were increased by factors of 50-, 24-, and 66-fold, respectively. All of the twisted acene syntheses reported here are suitable for the synthesis of at least gram quantities of these remarkable hydrocarbon materials. [ABSTRACT FROM AUTHOR]

Pentacene is one of the most versatile organic semiconductors. New synthetic strategies to construct the pentacene skeleton are imperative to produce pentacene derivatives with appropriate solubility, stability, and optoelectronic properties for various applications. This paper describes a template-directed approach to pentacene derivatives. In the retrosynthesis, the acene skeleton is viewed as a laddered double strand polyene instead of the more intuitive linearly fused hexagons. Based on this vision, the template strand of polyene is constructed with Wittig olefination, whereas the second strand is accomplished with Knoevenagel condensation to produce pentacene and tetracene derivatives. The synthetic scheme is flexible enough to generate an array of acene derivatives with substitution patterns that were hitherto difficult to access. Amphiphilic pentacene and tetracene derivatives were also synthesized by the template strategy. One pentacene based amphiphilic rod-coil molecule undergoes self-assembly to form helical wire structures that were visualized with TEM. [ABSTRACT FROM AUTHOR]

This study demonstrates how magnetic-field-dependent luminescence from organic films can be used to image the magnetic configuration of an underlying sample. The organic semiconductors tetracene and rubrene exhibit singlet exciton fission, which is a process sensitive to magnetic fields. Here, thin films of these materials were characterized using photoluminescence spectrometry, atomic force microscopy, and photoluminescence magnetometry. The luminescence from these substrate-bound thin films is imaged to reveal the magnetic configuration of underlying Nd-Fe-B magnets. The tendency of rubrene to form amorphous films and produce large changes in photoluminescence under an applied magnetic field makes it more appropriate for magnetic field imaging than tetracene. This demonstration can be extended in the future to allow simple microscopic imaging of magnetic structure. [ABSTRACT FROM AUTHOR]

Aryl-substituted o-carboranes have shown highly efficient solid-state emission in previous studies. To demonstrate color tuning of the solid-state emission in an aryl- o-carborane-based system, bis- o-carborane-substituted oligoacenes were synthesized and their properties were systematically investigated. Optical and electrochemical measurements revealed efficient decreases in energy band gaps and lowest unoccupied molecular orbital (LUMO) levels by adding a number of fused benzene rings for the extension of π-conjugation. As a consequence, bright solid-state emission was observed in the region from blue to near infrared (NIR). Furthermore, various useful features were obtained from the modified o-carboranes as an optical material. The naphthalene derivatives exhibited aggregation-induced emission (AIE) and almost 100 % quantum efficiency in the crystalline state. Furthermore, it was shown that the tetracene derivative with NIR-emissive properties had high durability toward photo-bleaching under UV irradiation. [ABSTRACT FROM AUTHOR]

Visualizing molecular crystalline domains and influence of substrate defects are important in understanding the charge transport in organic thin film devices. Vacuum evaporated tetracene films of four monolayers on hydrogen-terminated Si(001)-2 × 1 substrate, as a prototypical system, have been studied with ex situ atomic force microscopy (AFM), transverse shear microscopy (TSM), friction force microscopy (FFM), and low-energy electron microscopy (LEEM). Two differently oriented in-plane lattice domains are found due to the symmetry of the substrate lattice, with no visible azimuthal twist between adjacent molecular layers in surface islands, indicating significant bulk-like crystallization in the film. Meanwhile, two types of subdomains are observed inside of each in-plane lattice domain. The subdomains are anisotropic in shape, and their sizes and distribution are highly influenced by the substrate atomic steps. TSM and FFM measurements indicate that these subdomains result from molecule-tilt orderings within the bulk-like lattice domains. TSM evidently shows a sensitivity to probe vertical molecule-tilt anisotropy for the molecular crystals, in addition to its known ability to map the lateral lattice orientations. [ABSTRACT FROM AUTHOR]

Tetracene is an organic semiconductor with chemical formula C18H12 used in organic field effecttransistor (OFET) and organic light emitting diode (OLED). In this work, the molecular geometry (optimized bond lengths and bond angles), vibrational frequencies and intensities, HOMO-LUMO Energy gap and Atomic charge distribution of the Tetracene molecule in gas phase and in solution were calculated and reported. Restricted Hartree-Fock (RHF) and Density Functional Theory (DFT) with different basis sets were employed for the task. Windows version of Gaussian 03 software was used to perform all the calculations. The results obtained show that the bond length obtained using RHF has the lowest average value of 1.072Å and that obtained using DFT has the lowest average value of 1.085Å in gas phase. In Methanol, it is observed that at RHF level, the lowest average value was 1.075Å and at DFT level was 1.087Å. This shows that the values are a bit higher in methanol than in gas phase which implies that the bonds will be slightly stronger in gas phase than in methanol. The strongest bonds in tetracene molecule are those of C20-H28, C23-H29 and C24- H30 in both gas and methanol. The weakest bonds are those of C6-C12 and C6-C14.The bond angles were found to be so closed to 1200 at both levels of theory for all basis sets used suggesting that the molecule is planar benzene in which the C atoms are sp 2hybridized. The calculated HOMOLUMO energy gap shows that the molecule will be slightly more stable in chemical reaction in gas phase than in methanol. DFT values of the energy gap appeared to be closer to the reported experimental value of 2.6eV than those obtained by RHF. The atomic charges distribution was found to be very sensitive to the basis sets which presumably occur due to polarization. From the results obtained for vibrational frequencies, it shows that tetracene molecule would be more stable in gas phase that in methanol as a result of no imaginary frequency found in gas phase. This confirms the stability of the molecule as stated in the results of HOMO-LUMO energy gap. The calculated vibrational frequencies show that the most intense frequency was obtained to be 924.9862cm-1 at 146.7973KM/mole by RHF/3-21G in gas phase while at B3LYP/3-21G, it has the most intense frequency of about 474.1260cm-1 at 390.1077.2845MK/mole in methanol. [ABSTRACT FROM AUTHOR]

Singlet excitons fission (SF) into triplet excitons can enhance the efficiency of solar cells while reducing the heat loss in light absorption systems, but requires photostable materials with high triplet yield. We use Support Vector Regression (SVR) to establish a Quantitative Structure-Property Relationship (QSPR) model for perdition the triplet yield (Φ SF) of singlet fission materials (tetracene, pentacene, and perylenedimide derivatives, etc.). Minimum redundancy maximum relevance (mRMR), Floating front search (FFS) and Grid-search were used to select property molecular descriptions and parameter optimization, then the SVR model was established to predict the Φ SF of these compounds. The correlation coefficient R values of leave one out cross-validation (LOOCV) test and external validation test set were 0.88 and 0.93, respectively. The results show that the SVR-QSPR model has strong generalization ability, can predict the Φ SF value of singlet fission materials effectively and guide significance for developing highly efficient solar cells. [ABSTRACT FROM AUTHOR]

The multiphoton dissociation-ionization of tetracene at 355 nm using 6.5 nanosecond laser pulses, with and without argon as a carrier gas (CG), has been studied and compared. Ion fragments were analyzed in a time-of-flight mass spectrometer and separated according to their mass-to-charge ratio (m/z). The results show that the dynamic of photodissociation at ~1010 W⋅cm-2 intensities is strongly influenced by the CG. The suppression of fragmentation channels primarily those relating to the formation of the CHm+ (m = 2, 4), C2H4+ and C5H4+2 ions. CH5+ and CH6+ were observed which have not been reported before in photodissociation tetracene experiments.

Electronic transport properties of pure tetracene and rubrene molecules were studied using density functional theory within the non-equilibrium Green's function method. Transmission coefficient and I-V curve were calculated for both molecules. The comparison between transmission coefficients in tetracene and rubrene molecules shows that there are some extra peaks in rubrene that belong to phenyl rings which are attached to tetracene. Besides, we found that up to 2.2 V the current is almost the same in both rubrene and tetracene and above this value, the current in rubrene is increased in comparison to tetracene which is the result of attachment of additional phenyl groups in rubrene molecule. Finally, we detected that these two molecules exhibit negative differential resistance behavior in the range between 1.2 V and 2 V. [ABSTRACT FROM AUTHOR]

A tetracene dimer linked directly by a single bond has been successfully prepared by using electron withdrawing groups to improve the stability. The molecular structure of this dimer is characterized by 1 H NMR, MALDI-TOF mass spectroscopy, and elemental analysis. The minimized molecular structure and X-ray crystallography reveal that the tetracene subunits of this dimer adopt an orthogonal configuration. Its absorption spectrum differs significantly from that of its monomeric counterpart, suggesting the presence of strong interactions between the two tetracene subunits. The excited state of this dimer is delocalized on both two tetracene subunits, which is significantly different from that of orthogonal anthracene dimers, but similar with that observed for orthogonal pentacene dimer. Most of the excited states of this dimer decay by radioactive channels, which is different from the localized twisted charge transfer state (LTCT) channel of anthracene dimers and the singlet fission (SF) channel of pentacene dimers. The results of this research suggest that similar orthogonal configurations caused different propertied for acene dimers with different conjugation length. [ABSTRACT FROM AUTHOR]

Organic molecular crystals (OMCs) are of significant interest due to their potential use in transistors, photovoltaic devices, light emitting diodes, and other applications. However, conventional vacuum-based methods of growing crystalline OMC films are costly and provide limited control over crystal growth. In this study, we present a new method for preparing high performance single-crystal tetracene field-effect transistors under near-ambient conditions using organic vapor-liquid-solid (OVLS) deposition. We find that the mobility of OVLS-grown tetracene is comparable to high quality crystalline films prepared by physical vapor deposition. These results establish OVLS deposition as a relatively low cost, low substrate temperature, and ambient pressure method for growing high quality OMC films for device applications. [ABSTRACT FROM AUTHOR]

We observe the diffusion anisotropy difference between singlet and triplet excitons in organic crystals; that is, singlet and triplet excitons may have completely different spatial direction preference for diffusion. This phenomenon can be ascribed to the distinct dependence of different excitonic couplings (Coulomb Förster vs. exchange Dexter) existing in singlet and triplet excitons on their intermolecular distance and intermolecular orientation. Such a discovery provides insights for understanding the fundamental photophysical process in a vast range of organic condensed-phase systems and optimizing the efficiency of organic optoelectronic materials. [ABSTRACT FROM AUTHOR]

Charge transfer properties and adsorption mechanism of tetracene on silver are investigated based on DFT and SERS. Optimized geometries indicate distortions in hexagonal structure and deviations in co-planarity of carbon atoms due to the variations in bond angles and dihedral angles after adsorption on silver. Natural population analysis (NPA) confirms the charge transfers from silver to tetracene. Natural bond orbital (NBO) analysis illustrates the overlapping of π(C C) and π*(C C) orbitals and that of Ag valence orbitals with π(C C) of tetracene indicating charge transfers consequent to the process of adsorption. Theoretically simulated absorption spectrum has a surface plasmon resonance peak around 520 nm with major contributions arising from the charge transfers from HOMO to LUMO, HOMO-1 to LUMO and HOMO to LUMO + 2 excitations. Theoretically predicted SERS confirms the tilted orientation of tetracene on silver surface and the charge transfers reported. Chemically reactive sites were identified through Fukui functions. Localization of electron density arising from redistribution of electrostatic potential along with the reduction in bandgap of tetracene after adsorption on silver suggests its utility in the design of electro active organic semiconducting devices. Enhancement in dipole moment, polarizability and hyperpolarizability of tetracene after adsorption on silver indicates its potential in the design of novel NLO materials. [ABSTRACT FROM AUTHOR]

We present a direct study on the positioning and mobility of tetracene molecules in self-assembled methionine nanogratings on the Ag(111) surface. Our scanning tunneling microscopy observations reveal the preferential arrangement of isolated tetracene units within substrate stripes framed by one-dimensional methionine supramolecular rows, under the influence of long-range indirect interactions. However, the orientational order of the rod-like tetracene species is induced by the epitaxial fit to the underlying surface atomic lattice; and preferential alignment with the tetracene axes along the direction of the methionine grating could not be achieved. In scanning tunneling microscopy measurements under perturbative conditions, we find a one-dimensional diffusion of the confined tetracene along the direction of the molecular axis and restricted by the methionine gratings for non-parallel orientations. [ABSTRACT FROM AUTHOR]

Unsymmetrical 5,12-diethynyltetracene derivatives were synthesized from tetracenequinone by the addition of two types of ethynyllithium reagents, followed by reductive aromatization with SnCl2. These three-step reactions could be integrated into a one-pot process to give unsymmetrically substituted 5,12-diethynyltetracene derivatives in moderate yields. Some unsymmetrical 5,12-bis(phenylethynyl) tetracene derivatives were synthesized from 5-ethynyl-12- phenylethynyltetracene and iodobenzenes by Sonogashira coupling. This integrated process was applied to the synthesis of a ð-extended tetracene dimer. The photophysical properties of these compounds were examined by UV/Vis and fluorescence spectroscopy. [ABSTRACT FROM AUTHOR]