Tengying Ma

Theoretical exploration to second-order nonlinear optical properties of new hybrid complexes via coordination interaction between (metallo)porphyrin and [MSiW11O39]3− (M = NbV or VV) polyoxometalates

The second-order nonlinear optical (NLO) properties of hybrid complexes via coordination interaction between porphyrin and Keggin-type polyoxometalates (POMs) α-[MSiW11O39](3-) (M=Nb(V) or V(V)) are investigated by time-dependent density functional theory (TDDFT). The calculated results show that this kind of organic-inorganic hybrid complexes possesses remarkably large molecular second-order NLO polarizability, especially for the ZnP3P-C≡C-4-Py-[VSiW11O39](3-) (complex 4), which has a computed β0 value of 261,410 a.u. and might be an excellent second-order NLO material. The effects of substituted metal atom (M), metalloporphyrin, and π-conjugation on NLO response are analyzed, the substituted metal atom (M) with a large electronegativity, the metalloporphyrin, and the lengthening of π-conjugation are helpful in enhancing the optical nonlinearity of these systems, which reveal the general rules to design the complexes with large optical nonlinearities. Furthermore, the solvent effect largely affects the first-order hyperpolarizability of the complex, it implies that the second-order polarizabilities increased with the increase of the solvent in polarity.

Theoretical Exploration of Photoisomerization-Switchable Second-Order Nonlinear Optical Responses of Two-Dimendional Λ- and W-Shaped Polyoxometalate Derivatives of Dithienylperfluorocyclopentene

The switchable second-order nonlinear optical (NLO) properties on two-dimensional (2D) molecules based on Lindqvist-type [Mo6O19](2-) and dithienylperfluorocyclopentene (DTE) have been investigated at density functional theory (DFT) level. The CAM-B3LYP and M06-2X functionals were employed to study the switching behavior on NLO properties by photoisomerization reaction. The βtot value of system 2c (closed-ring form) is 15920.5 au, which is 150.1 times larger than that of the corresponding open-ring form (system 2o). The time-dependent DFT calculations predict that the charge transfer from DTE to polyoxometalate, and DTE intramolecular charge transfer in closed-ring systems effectively improve the static first hyperpolarizability. Furthermore, the Λ-shaped systems possess a larger u value than those of W-shaped systems owing to different orientation for substituent groups.

Theoretical studies on the photoisomerization-switchable second-order nonlinear optical responses of DTE-linked polyoxometalate derivatives.

The switchable second-order nonlinear optical (NLO) responses of the photoisomerized chromophore dithienylperfluorocyclopentene (DTE) derivatives, organic-inorganic systems of Lindqvist-type [Mo₆O₁₉]²⁻, have been investigated by tuning open-ring and the closed-ring form. In the present paper, we performed density functional theory (DFT) combined with finite field (FF) methods to calculate the second-order NLO coefficients for these organic-inorganic compounds. The calculations with three functionals (B3LYP/CAM-B3LYP/LC-BLYP) confirm the switching behavior on NLO properties by the photoisomerization reaction. The β(tot) value of system 2c (closed-ring form) is 10 times larger than that of its open-ring form (system 2o). And the other two pairs of systems also show good tuning properties. The ampliative ratio on second-order NLO coefficients between systems 2o and 2c (β(2c)/β(2o)) is 13 times as large as that of DTE (β(DTEc)/β(DTEo)). It suggests that introduction of [Mo₆O₁₉]²⁻ and organic groups to the DTE monomer effectively improve the conversion ratio of second-order NLO coefficients between the open-ring and closed-ring forms.

Theoretical investigation of armchair silicene nanoribbons with application in stretchable electronics

The electronic and transport properties of a series of 11-ASiNRs (armchair silicene nanoribbons) at different torsion angles were studied by using density functional theory combined with nonequilibrium Greens function method. Several key factors determining the transport properties, such as the electron transmission coefficient and band structure, have been discussed. The interesting results suggest that the transport properties of ASiNRs are insensitive to the torsional silicene nanoribbon configuration in the scattering region. With the increase of the torsion angle, the transmission coefficient is still well maintained within the limits of the torsion angle. Although the torsion angle is increased to 120°, the current dropped by just 22% compared to the initial 11-ASiNRs at a torsion angle of 0°. Furthermore, all the configurations of 11-ASiNRs in this study behave as conventional conductors with nearly linear current–voltage dependence. On the basis of these distinctive transport properties with metabolic structure, ASiNRs present potential promising applications in silicon-based electronic nanodevices.

Theoretical studies on tricarbonyl metal derivatives of Lindqvist-type polyoxometalate complexes: electronic structures and nonlinear optical properties

The density functional theory (DFT) method and natural bond orbital (NBO) analysis have been employed to investigate the electronic structures and second-order nonlinear optical (NLO) properties for tricarbonyl metal derivatives of a Lindqvist-type polyoxometalate, [Nb2W4O19M(CO)3]3−/2− (M = MnI, TcI, ReI, FeII, RuII and OsII). The position of the tricarbonyl metal ligand and the substitution of different metal atoms M have an influence on the electronic absorption spectra and NLO responses of all complexes. Among the three isomers of [Nb2W4O19Mn(CO)3]3−, the β0 value of isomer 1a is the largest, which is 1.4 times and 2.3 times larger than those of isomers 1b and 1c, respectively. The β0 value also depends on the tricarbonyl metal M, the β0 value decreases in the order M = Ru > Re > Fe > Os > Mn > Tc. In addition, the analysis of the main transition orbitals shows that the tricarbonyl metal ligand acts as an electron donor in [Nb2W4O19M(CO)3]3−/2− (M = MnI, TcI, ReI, RuII and OsII), while the [Fe(CO)3]2+ ligand acts as an electron acceptor in [Nb2W4O19Fe(CO)3]2−.

Theoretical exploration to the cation effect on the second-order nonlinear optical properties of Strandberg-type polyoxometalates

The combination of cations with octahedral coordinated d0 transition metal ions has been proved to be an effective way for designing new polar materials. So we investigate the second-order nonlinear optical (NLO) properties of Strandberg-type polyoxometalates (POMs) with alkali metal cations M6Mo5X2O23 (M = K+, Rb+, Cs+; X = P, As) and M4Mo5X2O21 (M = K+, Rb+, Cs+; X = S, Se, Te) by density functional theory (DFT) method. The calculated results show that this kind of Strandberg-type POMs possesses remarkably large molecular second-order NLO polarizability, especially for the Cs6Mo5P2O23 (system Ic), which has a computed β0 value of 12526 a.u. and might be an excellent second-order NLO material. Moreover, the cations have important impact on the second-order NLO polarizabilities. Therefore, a careful choice of appropriate cations may allow the control of the second-order NLO response on these Strandberg-type POMs, which may provide a new route to design efficient NLO materials.

Theoretical design of organic-inorganic hybrids based on hexamolybdate toward high performance dye-sensitized solar cells

Abstract The electronic structures, absorption spectra and photovoltaic (PV) performance of four dyes based on triphenylamine and polyoxometalate (POM) organic–inorganic hybrids for p-type dye-sensitised solar cells have been discussed by density functional theory (DFT) and time-dependent DFT calculations. In the four designed dyes, the triarylamine and carbazole take the role of the electron donor and the POMs act as the electron acceptor. It was found that introduction of electron donating groups (diphenylamine group and carbazole) into the triarylamine unit enabled better PV performance. This work is expected to be helpful for designing triarylamine–POM hybrid dyes with target properties.