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Browsing Chemistry by Author "Balanay, Mannix P."
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Item Open Access DFT/TD-DFT molecular design of porphyrin analogues for use in dye-sensitized solar cells(2008) Balanay, Mannix P.; Kim, Dong HeeDensity functional theory (DFT) and time-dependent DFT calculations have been employed to model Zn meso-tetraphenylporphyrin (ZnTPP) complexes having different b-substituents, in order to design an efficient sensitizer for dye-sensitized solar cells. To calculate the excited states of the porphyrin analogues, at least the TD-B3LYP/6-31G* level of theory is needed to replicate the experimental absorption spectra. Solvation results were found to be invariant with respect to the type of model used (PCM vs. C-PCM). Most of the electronic transitions based on Gouterman’s four-orbital model of ZnTPP-A and ZnTPP-B are p - p* transitions, so that cell efficiency can be enhanced by increasing the p-conjugation and electron-withdrawing capability of the bsubstituent. This proposition was tested by inserting thiophene into the b-substituent of ZnTPP-A to form a new analogue, ZnTPP-C. Compared with ZnTPP-A and ZnTPP-B, ZnTPP-C has a smaller band gap, which brings LUMO closer to the conduction band of TiO2, and a red-shifted absorption spectrum with higher extinction coefficients, especially in the Q-band positionItem Open Access Experimental and theoretical analysis of organic dyes having a double D-π-A configurations for dye-sensitized solar cells(Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 2017-02-15) Balanay, Mannix P.; Choi, Kyu Seok; Lee, Sang Hee; Kim, Dong HeeTwo spiro-like organic dyes linked at the thiophene bridge (KS-11 and KS-12) together with the original rod-shaped D-π-A configuration (C1) were designed, synthesized, and characterized based on their electronic structure, and determine the photophysical and photovoltaic properties for its application in dye-sensitized solar cells. Compared to C1, the double D-π-A spiro-like configuration, which consists of two separated light-harvesting moieties, was found to be beneficial to photocurrent generation provided that they are separated properly to prevent intramolecular exciton annihilation. This was observed when KS-11, which is linked at the β-position of the thiophene moiety of D-π-A, was compared with KS-12, where the two D-π-A are linked with an additional thiophene using a α-β linkage. The results show that KS-12 produced a 20% and 17% increase in photovoltaic efficiency under simulated AM 1.5G solar irradiation compared to KS-11 and C1, respectively. This increase in photovoltaic performance is credited mostly to the reduction of recombination effects and the increase in the density of states at the semiconductor surface due to high dye loading and better charge-transfer properties.Item Metadata only Molecular engineering of donor–acceptor co-polymers for bulk heterojunction solar cells(Computational and Theoretical Chemistry, 2015-03-01) Balanay, Mannix P.; Kim, Dong Hee; Mannix P., BalanayAbstract We report a computational modeling, based on DFT and TD-DFT methodologies, on the structural, electronic, and optical properties of different donor–acceptor co-polymer system in bulk heterojunction solar cells. The donor moieties that were considered were the derivatives of thienocyclopentathiophene, fluorene, and thienobenzothiophene. We utilized for the acceptor groups the moieties of thieno[3,4-b]pyrrole-4,6-dione; thieno[3,4-b] thiophene-4,6-dione; tetrafluoro-1,3-dihydrothieno[3,4-c]thiophene and its non-fluorinated counterpart; various electron-donating substituents within the fused π-conjugated polymer system; and 3-fluoroselenophenothiophene. Among the donor–acceptor combination, the best in terms of molecular energy levels, energetic driving force, maximum absorption, calculated open-circuit voltage, reorganization energies, ionization potential, and electron affinity are poly[(bisthieno(bisthieno[3,2-b:2′,3′-d]thiophene)- alt-(5-alkyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione)] and poly[(4,8-dimethyl[1,3] oxazolo[5,4-f][1,3]benzoxazole)- alt-(thieno[3,4-d]pyrimidine)].Item Metadata only Theoretical design of triphenylamine-based derivatives with asymmetric D–D–π–A configuration for dye-sensitized solar cells(Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015-04-05) Balanay, Mannix P.; Enopia, Camille Marie G.; Lee, Sang Hee; Kim, Dong Hee; Mannix P., BalanayAbstract The use of theoretical techniques in the structural development of dye-sensitized solar cells helps in the efficient screening of the dyes. To properly rationalize the dye’s design process, benchmark calculations were conducted using long-range corrected exchange–correlation (xc) functionals with varying separation parameters to be able to predict the excited-state energies of triphenylamine-based dyes, namely: PPS, PSP, and PSS, wherein they differ at the π-conjugated bridge using thiophene and/or phenyl moieties. The results show that LC-ωPBE xc functional with an optimized parameter provided better correlation with the experimental results compared to the other functionals. The relative shifts of the absorption spectra, light harvesting efficiency, normal dipole moments, as well as the ionization potentials and electron affinities of the dyes were well-correlated with the experimental data. A new set of dyes was designed in an effort to increase its solar cell efficiency that was patterned after PSS with an additional donor moiety such as fluorene, cyclopentaindole, and pyrene attached asymmetrically at the triphenylamine ring. Among the newly designed dyes, analogs that contain 4-phenyl-1,2,3,4-tetrahydrocyclopenta[b]indole (I) and pyrido[2,3,4-5-imn]phenanthridine-5,10(4H,9H)-dione (P2) as the additional donor moiety produced the best photophysical properties and charge-transfer characteristics for a promising dye for solar cell applications.