Search results for "Electron affinity"
showing 10 items of 42 documents
Adsorption of gold clusters on metal-supported MgO: Correlation to electron affinity of gold
2007
Adsorption of ${\mathrm{Au}}_{N}$ clusters $(N=1\char21{}6)$ on a bulk MgO(001) surface and on an ultrathin (3 ML) MgO(001) film supported by Mo metal is investigated via density-functional theory calculations. Comparison of the two substrates unambiguously shows that the gold clusters adsorbed on $\mathrm{Mg}\mathrm{O}∕\mathrm{Mo}$ turn into singly charged cluster anions ${\mathrm{Au}}_{N}^{\ensuremath{\delta}}$, $\ensuremath{\delta}\ensuremath{\approx}\ensuremath{-}1$. Their structures and internal charging patterns are analogous to singly charged, planar, gas-phase cluster anions ${\mathrm{Au}}_{N}^{\ensuremath{-}}$. The adsorption energy has prominent size-dependent odd-even oscillation…
Relationship between Electron Affinity and Half-Wave Reduction Potential: A Theoretical Study on Cyclic Electron-Acceptor Compounds.
2016
A high-level ab initio protocol to compute accurate electron affinities and half-wave reduction potentials is presented and applied for a series of electron-acceptor compounds with potential interest in organic electronics and redox flow batteries. The comprehensive comparison between the theoretical and experimental electron affinities not only proves the reliability of the theoretical G3(MP2) approach employed but also calls into question certain experimental measurements, which need to be revised. By using the thermodynamic cycle for the one-electron attachment reaction A+e- →A- , theoretical estimates for the first half-wave reduction potential have been computed along the series of ele…
Cruciform Electron Acceptors Based on Tetraindeno-Fused Spirofluorene
2017
Two cruciform tetraindenospirofluorene-based acceptors embedding carbonyl (Spiro-4O) and dicyanovinylene (Spiro-8CN) functionalities are synthesized in high yields. Single-crystal X-ray analysis reveals a one-dimensional π–π stacking arrangement for Spiro-4O, while Spiro-8CN adopts a unique two-dimensional isotropic π-interaction. Cyclic voltammetry suggests a high electron affinity of −3.76 eV for Spiro-8CN. Such a packing motif and low LUMO energy for Spiro-8CN are important for bulk electron transport.
A theoretical study of neutral and reduced tetracyano-p-quinodimethane (TCNQ)
2004
Abstract The molecular structure of neutral, anionic, and dianionic tetracyano- p -quinodimethane (TCNQ), as well as the electron affinity of TCNQ, have been studied with HF, MP2, and different density functional theory (DFT) procedures. The optimized geometries compare well with the available experimental data, although the C N bond distance is not correctly described at the MP2 level. The calculated parameters are rather insensitive to the basis set employed, and the addition of diffuse functions does not yield significant changes. When the extra electrons are added, the central ring of TCNQ progressively becomes more aromatic. Compared with the CCSD(T) estimate, the value of the adiabati…
Binding and isomerization energies for the Cu/CN and Cu(I)CN interactions
1993
Abstract Binding and isomerization energies of the CuCN, CuNC, CuCN+, and CuNC+ systems were investigated by means of a multireference CI perturbatively selected, MRCI-PS approach. The inclusion of the main dynamical correlation effects are evaluated. The binding energies for CuCN and CuNC are 4.37 and 4.03 eV, respectively, and those for CuCN+ and CuNC+ are 0.08 and 1.61 eV. Calculated isomerization energies are 7.86 and 35.98 kcal/mol for CuCN and Cu(I)CN isomerizations, respectively.
3,3'-Bicarbazole structural derivatives as charge transporting materials for use in OLED devices
2018
In this study we report novel 3,3′-bicarbazole based charge transporting materials mainly designed for a use in systems containing phosphorescent iridium (III) complex emitters. A low-cost oxidative coupling reaction using FeCl3 was employed in the synthesis of 3,3′-bicarbazole compounds. Different derivatives of 3,3′-bicarbazole with 4-ethoxyphenyland ethyl- substituents at 9,9′- positions and (2,2-diphenylhydrazono)methyl- and 4-(dimethylamino)styryl- substituents at 6,6′- positions were synthesized. Obtained (2,2-diphenylhydrazono)methyl- derivatives exhibit glass transition temperatures that are sufficient for applications in electronic devices. Thin amorphous films of good optical qual…
Stilbenoid phosphors with increased electron affinity: sulfones as electron accepting groups
2001
Stilbenoid compounds are one of the preferred classes of luminescent materials for the use in light emitting diodes (LEDs). A problem connected with the use of poly(phenylenevinylene) (PPV) in LEDs is the unbalanced charge carrier transport, electron injection from aluminium and electron transport properties are only poor. The substitution with electron accepting groups like nitriles is a suitable way to lower the LUMO level of the chromophore. The electron withdrawing strength of sulfones is comparable to cyanides and the second binding site is useful to attach solubilising side chains. A two-step synthesis of model compounds and polymers from ethene and sulfonyl dibromobenzene and bromo a…
Photoelectrical properties of indandione fragment containing azobenzene compounds
2014
Organic materials are becoming more popular due to their potential application in electronics. Low molecular weight materials possible produce from solution are in special consideration. It gives the possibility to avoid both thermal evaporation in vacuum, and use of polymers in thin film preparation process. Indandione fragment containing azobenzene compounds are one of such materials. These compounds are good candidates for use in design of novel molecular electronic devices due to their possibility to form amorphous structure from solution thus allowing developing flexible, small size systems with low production costs. In this work three indandione fragment containing azobenzene compound…
Photovoltaic effect in bulk heterojunction system with glass forming indandione derivative DMABI-6Ph
2018
The aim of the work is to evaluate possible use of 2-[[4-(bis(2-trityloxyethyl)amino)phenyl]methylene]indane-1,3-dione (DMABI-6Ph) as light absorbing material for solar cells. DMABI-6Ph is a perspective material due to its good photoelectrical, thermal and chemical properties. The main advantage of DMABI-6Ph is its ability to form amorphous films by wet-casting methods thus allowing using the compound in organic solar cells made from solution. For now most popular materials for solution processable solar cells are polymer P3HT and fullerene derivative PCBM, but lot of investigations are in the field of new low molecular weight materials to replace the polymer. Photoelectrical measurements w…
On the electron affinity of TCNQ
2004
The electron affinity of 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) has been studied with density functional theory and coupled cluster (CC) procedures. The adiabatic electron affinity of TCNQ calculated with the B3LYP method is about 1 eV higher than the available experimental value. At the CCSD(T) level, the theoretical result is overestimated by more than 0.4 eV. The electron affinity computed for TCNQ is larger than that obtained for tetracyanoethylene at all levels of calculation, exactly the opposite of what is observed experimentally. Accordingly, a call for an additional empirical measurement of such a property is made.