Semiconductor charge transfer (CT) cocrystals are an emerging class of molecular materials which combines the characteristics constituent molecules in order to tune physical properties. Cocrystals can exhibit polymorphism, but different stoichiometries donor–acceptor (DA) pair also give structures. In addition, structures donor and acceptor as pristine compounds influence resulting cocrystal forms. We report a structural study on several CT obtained by combining polyaromatic hydrocarbon...

A computational protocol for the calculation of local (Holstein) and nonlocal (Peierls) carrier-phonon coupling in molecular organic semiconductors is presented applied to orthorhombic rubrene (5,6,11,12-tetraphenyltetracene). In phonon description, rigid molecule approximation removed, allowing mixing low-frequency intramolecular modes with intermolecular (lattice) phonons. Notwithstanding, a rather clear distinction remains between phonons, which essentially modulate transfer integral from...

Novel fused donor-acceptor dyad (TTF-Q or D-A) and acceptor-donor-acceptor triad (Q-TTF-Q A-D-A) incorporating the donor tetrathiafulvalene (TTF) acceptor p-benzoquinone (Q) have been synthesized. The solution UV-vis spectra of these molecules display a low-energy absorption band that is attributed to an intramolecular charge transfer between both antagonistic units. presence reversible oxidation reduction waves for moieties was shown by cyclic voltammetry, in agreement with ratio...

Charge ordering in the (TMTTF)2X salts with centrosymmetric anions (X = PF‾6 , AsF‾6 SbF‾6 ) leads to a ferroelectric state around 100 K. For first time and great completeness, intra- intermolecular vibrational modes of have been investigated by infrared Raman spectroscopy as function temperature pressure for different polarizations. In this original paper, we explore development amount charge disproportionation coupling electronic degrees freedom counterions underlying lattice. The methyl...

The impact of the anthropic activities in Antarctica is a concerning issue. According to Scientific Committee on Antarctic Research, attention has be paid next-generation contaminants deriving from both long-range atmospheric transport and local sources. In this study, capabilities transmission electron microscopy with energy-dispersive X-ray spectroscopy Raman micro-spectroscopy were exploited evaluate size, morphology, chemical composition small micro- nanoparticles, as well their...

Crystals of tetracene have been studied by means lattice phonon Raman spectroscopy as a function temperature and pressure. Two different phases (polymorphs I II) obtained, depending on sample preparation history. Polymorph is the most frequently grown phase, stable at ambient conditions. Application pressure above $1\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ yields polymorph II, which also obtained cooling below $140\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. However, conditions for inducing phase...

The computational protocol we have developed for the calculation of local (Holstein) and non-local (Peierls) carrier-phonon coupling in molecular organic semiconductors is applied to both low temperature high bulk crystalline phases pentacene. electronic structure calculated by semimpirical INDO/S (Intermediate Neglect Differential Overlap with Spectroscopic parametrization) method. In phonon description, rigid molecule approximation removed, allowing mixing low-frequency intra-molecular...

We report two hitherto unknown polymorphs of the charge transfer (CT) cocrystal perylene:tetracyanoquinodimethane (TCNQ) grown by physical vapor transport (PVT) in argon atmosphere. One polymorphs, named β, has stoichiometry 1:1 and adds to three known structures with (α), 2:1, 3:1. Interestingly, below (280 ± 10) K β structure undergoes a phase transition what we refer as γ polymorph, halving unit cell reduction symmetry from monoclinic triclinic. Both new crystal present alternating stacks...

Organic charge-transfer (CT) crystals constitute an important class of functional materials, characterized by the directional interaction between π -electron Donor (D) and Acceptor (A) molecules, with formation one-dimensional ...DADAD... stacks. Among many different often unique phenomena displayed this crystals, Neutral-Ionic phase transition (NIT) occupies a special place, as it implies collective electron transfer along stack. The analysis such complex yet fascinating phenomenon has...

The design of efficient organic electronic devices, including OLEDs, OPVs, luminescent solar concentrators, etc., relies on the optimization relevant materials, often constituted by an active (functional) dye embedded in a matrix. Understanding solid state solvation (SSS), i.e. how properties are affected matrix, is therefore issue fundamental and technological relevance. Here extensive experimental theoretical investigation presented shedding light this, somewhat controversial, topic....

Lattice-phonon confocal Raman mapping is a powerful technique to probe the crystal structure of polymorphs organic semiconductors. This fast, reliable, and capable monitoring physical modifications phase inhomogeneities in domains at micrometer scale. Applying pentacene crystals (see Figure) shows that are not confined surface, but penetrate into crystal.

We have used confocal micro Raman spectroscopy, atomic force microscopy (AFM), and x-ray diffraction (XRD) to investigate pentacene films obtained by vacuum deposition on SiO${}_{2}$ substrates. These methods allow us follow the evolution of lattice structure, vibrational dynamics, crystal morphology during growth from monolayer, TF, and, finally, bulk crystal. The measurements, supported AFM XRD data, indicate that film depends rate. High rates yield two-dimensional nucleation...

The present study aimed to detect microplastics in feline placentas and fetuses the early stage of pregnancy. For this study, 8 pregnant queens were evaluated. A standardized protocol for digestion biological matter was used, as well a plastic-free approach sample collection manipulation. Microplastics investigated by means Raman spectroscopy, with aim identifying their composition. Four eight animals contaminated, total 19 detected both fetal placental samples. Specifically, from cats 4 7...

Organic charge transfer (CT) cocrystals are a wide class of 1-D materials based on stacks planar π-electron donor (D) and acceptor (A) molecules overlapping their frontier orbitals due to the CT interaction. Most crystals have either segregated or mixed stack motif: in stacks, D A form separate columns, while alternate along same stack. Although often display polymorphism, very few D-A pairs known crystallize with both motifs. Here, we present new complex presenting phases, strong...

We have performed a lattice dynamics calculation to compute the “inherent structures” of minimum potential energy for pentacene, starting from available X-ray data. The shows that two distinct bulk crystalline phases pentacene exist, with very subtle structural differences but clearly different phonon spectra. method crystal growth (from solution or vapor) is not determining factor obtaining either structure.

Single crystals of pentacene with different morphologies (polymorphs C and H) have been studied by Raman spectroscopy as a function temperature from 79 to 300 K. All active lattice modes range low-frequency intramolecular identified assigned. The experiments are compared quasi harmonic dynamics (QHLD) calculations the crystallographic structures vibrational frequencies temperature. Experiments both indicate that two polymorphs stable over wide range.

We report for the first time lattice phonon Raman spectra of organic semiconductor 5,6,11,12-tetraphenyl-tetracene (rubrene). Polarized were recorded symmetry assignments. A comparison experimental data with quasi harmonic dynamics calculations, performed starting from X-ray structures, is given. It shown that can only be explained by invoking an efficient coupling between vibrations and low energy intramolecular modes. Calculations also show crystal structure corresponds to a stable...

Raman microscopy in the lattice phonon region coupled with X-ray diffraction have been used to study polymorphism crystals and microcrystals of organic semiconductor 9,10-diphenylanthracene (DPA) obtained by various methods. While solution grown specimens all display well-known monoclinic structure widely reported literature, varying growth conditions two more polymorphs obtained, either from melt or sublimation. By injecting water as a nonsolvent DPA solution, one new was predominantly...

We report comprehensive Raman and infrared investigations of charge-order (CO) fluctuations in the organic metal ${\ensuremath{\beta}}^{\ensuremath{'}\ensuremath{'}}$-(BEDT-TTF)${}_{2}$SF${}_{5}$CHFSO${}_{3}$ superconductor ${\ensuremath{\beta}}^{\ensuremath{'}\ensuremath{'}}$-(BEDT-TTF)${}_{2}$SF${}_{5}$CH${}_{2}$CF${}_{2}$SO${}_{3}$. The charge-sensitive vibrational bands are analyzed through an extension well-known Kubo model for spectral signatures equilibrium between two states. At room...

In the salt formed by bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with $[{\mathrm{Mo}}_{6}{\mathrm{O}}_{19}{]}^{2\mathrm{\ensuremath{-}}}$ anion, ${\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F}}^{+}$ cations form quasi-isolated dimers. For this reason $({\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F})}_{2}{\mathrm{Mo}}_{6}{\mathrm{O}}_{19}$ has been selected to experimentally evaluate microscopic parameters....

Abstract The charge‐fluctuating and charge‐ordered states in metallic, insulating superconducting bis(ethylenedithio)tetrathiafulvalene (BEDT‐TTF) salts are characterized through the analysis of infrared (IR) spectral region relevant to CC antisymmetric stretch, b 1 ν 22 . This shows dramatic changes band intensity band‐shape by varying temperature. observed features can be understood on basis an extension well‐known Kubo model for signatures equilibrium between two states. two‐orders...

We show that the development of highly accurate density functional theory calculations coupled to low-frequency Raman spectroscopy constitutes a valid method for polymorph characterization alternative/complementary X-ray. The is applied here temperature-induced, first-order phase transition coronene, known long time, but has remained structurally uncharacterized due crystal breaking during process. astonishing fidelity calculated spectra experiments allows us unambiguously identify...