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Spectrochim Acta A Mol Biomol Spectrosc ; 133: 514-20, 2014 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-24983919


Alkyne bridged porphyrin sensitizers have attracted great attention in the field of dye-sensitized solar cells (DSSCs) because of their excellent photo-to-electric conversion efficiencies, among which YD2 has reached 11% while YD2-o-C8 has reached 11.9% solely and 12.3% co-sensitized with other sensitizers. Design and screening of porphyrin sensitizer candidates with wider electronic absorption spectra to further improve the photo-to-electric conversion efficiencies of corresponding solar cells is still very important. Twenty novel alkyne bridged zinc porphyrin sensitizer candidates composed of the donors diarylamino-, tri-4-methylphenyl-, tri-hydroxyl- and tri-amino-substituted zinc porphyrins as well as the selected acceptors E, M, Q, R and S have been designed and calculated at the density functional B3LYP level. YD2 and YD2-o-C8 are also calculated at the same level for comparison. The result shows that the sensitizer candidates all have smaller HOMO-LUMO gaps as well as wider and red-shifted absorption bands than those of YD2 and YD2-o-C8. Most of the sensitizer candidates have appropriate HOMO and LUMO energy levels relative to the redox potential of the mediator and the TiO2 conduction band, showing that they are promising to provide comparable or even higher photo-to-electric conversion efficiencies than 11% of YD-2 or 11.9% of YD2-o-C8.

Alquinos/química , Corantes/química , Metaloporfirinas/química , Fontes de Energia Elétrica , Elétrons , Teoria Quântica , Energia Solar
Spectrochim Acta A Mol Biomol Spectrosc ; 118: 564-71, 2014 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-24084486


Alkyne bridged porphyrins have been proved very promising sensitizers for dye-sensitized solar cells (DSSCs) with the highest photo-to-electric conversion efficiencies of 11.9% solely and 12.3% co-sensitized with other sensitizers achieved. Developing better porphyrin sensitizers with wider electronic absorption spectra to further improve the efficiencies of corresponding solar cells is still of great significance for the application of DSSCs. A series of triphenyl zinc porphyrins (ZnTriPP) differing in the nature of a pendant acceptor group and the conjugated bridge between the porphyrin nucleus and the acceptor unit were modeled and their electronic and spectral properties calculated using density functional theory. As compared with each other and the experimental results of the compounds used in DSSCs previously, the molecules with a relatively longer conjugative linker and a strong electron-withdrawing group such as cyanide adjacent to the carboxyl acid group seem to provide wider electronic absorption spectra and higher photo-to-electric conversion efficiencies. The dye candidates ZnTriPPE, ZnTriPPM, ZnTriPPQ, ZnTriPPR and ZnTriPPS designed in the current work were found promising to provide comparable photo-to-electric conversion efficiencies to the record 11.9% of the alkyne bridged porphyrin sensitizer YD2-o-C8 reported previously.

Alquinos/química , Benzeno/química , Corantes/química , Metaloporfirinas/química , Fontes de Energia Elétrica , Elétrons , Energia Solar , Tiofenos/química
ScientificWorldJournal ; 2013: 292787, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24282378


Among the noncompact matrix Lie groups, the special Euclidean group and the unipotent matrix group play important roles in both theoretic and applied studies. The Riemannian means of a finite set of the given points on the two matrix groups are investigated, respectively. Based on the left invariant metric on the matrix Lie groups, the geodesic between any two points is gotten. And the sum of the geodesic distances is taken as the cost function, whose minimizer is the Riemannian mean. Moreover, a Riemannian gradient algorithm for computing the Riemannian mean on the special Euclidean group and an iterative formula for that on the unipotent matrix group are proposed, respectively. Finally, several numerical simulations in the 3-dimensional case are given to illustrate our results.

J Mol Graph Model ; 38: 82-9, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23085158


A series of unsymmetrical phthalocyanine sensitizer candidates with different donor and acceptor substituents, namely ZnPcBPh, ZnPcBOPh, ZnPcBtBu, ZnPcBN(Ph)2, ZnPcBNHPh, ZnPcBNH2, ZnPcBNHCH3 and ZnPcBN(CH3)2, were designed and calculated using density functional theory (DFT) and time-dependent DFT calculations. The molecular orbital energy levels, the molecular orbital spatial distributions and the electronic absorption spectra of the ZnPcB series molecules were compared with those of TT7 and TT8 to reveal the substituent effects of different donor and acceptor groups on the phthalocyanine compounds and select good sesitizer candidates. The results show that some of these compounds have considerably smaller orbital energy gaps, red-shifted absorption bands and better charge-separated states, causing them to absorb photons in the lower energy region. Several new absorption bands emerge in the 400-600 nm region, which makes it possible for them to become panchromatic sensitizers. This characteristic is superior to the phthalocyanine sensitizers reported previously, including the current record holder, PcS6. The sensitizer candidates screened in the current work are very promising for providing good performance and might even challenge the photon-to-electricity conversion efficiency record of 4.6% for phthalocyanine sensitizers.

Corantes/química , Elétrons , Indóis/química , Compostos Organometálicos/química , Fótons , Modelos Moleculares , Teoria Quântica , Energia Solar/estatística & dados numéricos , Eletricidade Estática , Luz Solar , Fatores de Tempo
J Mol Graph Model ; 34: 1-9, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22306409


Computational screening of new dyes is becoming an extremely powerful tool, especially when associated with experimental synthetic efforts that might eventually lead to new and more efficient products. Nine novel unsymmetrical zinc phthalocyanine complexes derived from TT1 were designed as sensitizer candidates for dye-sensitized solar cells with three peripheral -CH3, -OH, -OCH3, -OPh, -NH2, -NHCH3, -N(CH3)2, -NHPh and -N(Ph)2 substituents as the donors and a carboxyl group as the acceptor. The molecular orbital and the electronic absorption spectra properties of these compounds were studied and compared to those of TT1 using the density functional theory and time-dependent density functional theory calculations at B3LYP level with the LANL2DZ basis set. The novel candidates bearing the -NH2, -NHCH3, -N(CH3)2, -NHPh and -N(Ph)2 moieties as the donors were found to be very promising for providing higher efficiencies than that of TT1 or even the current 4.6% efficiency record held by PcS6. They have higher LUMO levels, smaller energy gaps and red-shifted absorption bands compared to those of TT1. The new absorption bands emerging in 450-600 nm regions may promote ZnPcL-NH2, ZnPcL-NHCH3, ZnPcL-N(CH3)2, ZnPcL-NHPh and ZnPcL-N(Ph)2 from near infrared to panchromatic sensitizers. Further experimental synthetic efforts are in progress in our group to validate the predictions in this report.

Simulação por Computador , Indóis/química , Modelos Químicos , Compostos Organometálicos/química , Processos Fotoquímicos , Eletroquímica , Modelos Moleculares , Energia Solar , Termodinâmica