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Strategic Design of Bacteriochlorins as Possible Dyes for Photovoltaic Applications
Balanay, Mannix P.,Kim, Dong Hee American Chemical Society 2017 The Journal of physical chemistry A Vol.121 No.35
<P>Bacteriochlorin-based dyes, having a push-pull type of configuration similar to that of the YD2 dye, were theoretically designed based on modification of the macrocycle and pi-conjugated bridge for use in dye-sensitized solar cells. Various parameters were assessed to determine its structure-property relationships, such as the absorption profile based on time-dependent density functional theory, nonlinear optical properties from (hyper)polarizability data, ground- and excited-state oxidation potentials, and the electronic properties of the free and adsorbed dyes. On the basis of the results, the most appropriate macrocycle would be 7,7,17,17-tetramethy1-7H,8H,17H,18H-porphyrin and, for its pi-conjugated bridge, either thieno[3,2-b]thiophene, dithieno[3,2-b:2',3'-d]-thiophene, or 4,4-diisopropy1-4H-cyclop enta [2,1-b:3,4-b'] dithiophene. These newly designed dyes produced an absorption spectra having a range of 300-800 nm, which could likely increase the light harvesting efficiency. It has better nonlinear properties than the reference, thereby ensuring higher charge-transfer properties. Also, the dye regeneration efficiency is within the optimized value of 0.2 of voltage. This shows that through theoretical approach we can deductively design process in the design of dyes to produce efficient dye-sensitized solar cells.</P>
Balanay, Mannix P.,Kim, Se-Mi,Lee, Mi-Jung,Lee, Sang-Hee,Kim, Dong-Hee Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.9
The conformational and electronic properties of 2-cyano-3-(thiophen-2-yl)acrylic acid (TCA) in analogues used as sensitizers in dye-sensitized solar cells was examined using density functional theory (DFT) and natural bond orbital analysis methods. A relaxed potential energy surface scan was performed on NKX-2677 by rotating the C-C bond between the thiophene and cyanoacrylic acid which yielded activation energy barriers of about 13 kcal/mol for both E and Z configurations. The most stable conformation of all the analogues was E-180 except for NKX-2587 which has an electrostatic repulsion between the oxygen of the coumarin and the nitrogen of the cyanoacrylic acid. The increase in the electron delocalization between the thiophene and cyanoacrylic acid influences the stability for most of the analogues. But for NKX-2600, even though there was a greater deviation from the planarity of TCA, the stability was mainly due to the presence of a weak hydrogen bond between the hydrogen of the methyl group of the amine located in the donor moiety and the nitrogen of the cyanoacrylic acid. The vertical excitation energies of the analogues containing TCA were calculated by time-dependent DFT method. There were slight differences in its vertical excitation energies but the oscillator strengths vary significantly especially in the case of NKX-2600.
Balanay, M.P.,Kim, D.H. Elsevier Scientific Pub. Co 2014 Computational & theoretical chemistry Vol.1029 No.-
In this study, density functional theory is used to evaluate the noncovalent bond interactions between the dye and iodine. We consider the binding of I<SUB>2</SUB> to multiple electron-donating sites in organic sensitizers containing furan or thiophene at the π-conjugated bridge. The results show that the trend in the stabilization energy based on the second-order perturbation theory analysis of the Fock matrix in NBO increases with O...I<S...I<N...I noncovalent interactions. The trend of interaction energies decreases in the order of C209>C213>C214. This trend suggests that the thiophene-containing dyes and the longer π-bridge conjugation allows more stable interactions with the iodine species, thus increasing the concentration of the redox couple at the surface of the semiconductor. This is consistent with the observed open-circuit voltages of the dyes. This work highlights the importance of the use of multiple iodine species interacting with the dye when considering recombination reactions with the electrolyte which ultimately affects the device efficiency.
Balanay, M.P.,Enopia, C.M.G.,Lee, S.H.,Kim, D.H. Pergamon 2015 Spectrochimica acta. Part A, Molecular and biomole Vol.140 No.-
<P>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 pi-conjugated bridge using thiophene and/or phenyl moieties. The results show that LC-omega PBE 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. (C) 2015 Elsevier B.V. All rights reserved.</P>
Mannix P. Balanay,Se-Mi Kim,Mi Jung Lee,이상희,김동희 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.9
The conformational and electronic properties of 2-cyano-3-(thiophen-2-yl)acrylic acid (TCA) in analogues used as sensitizers in dye-sensitized solar cells was examined using density functional theory (DFT) and natural bond orbital analysis methods. A relaxed potential energy surface scan was performed on NKX-2677 by rotating the C-C bond between the thiophene and cyanoacrylic acid which yielded activation energy barriers of about 13 kcal/mol for both E and Z configurations. The most stable conformation of all the analogues was E-180 except for NKX-2587 which has an electrostatic repulsion between the oxygen of the coumarin and the nitrogen of the cyanoacrylic acid. The increase in the electron delocalization between the thiophene and cyanoacrylic acid influences the stability for most of the analogues. But for NKX-2600, even though there was a greater deviation from the planarity of TCA, the stability was mainly due to the presence of a weak hydrogen bond between the hydrogen of the methyl group of the amine located in the donor moiety and the nitrogen of the cyanoacrylic acid. The vertical excitation energies of the analogues containing TCA were calculated by time-dependent DFT method. There were slight differences in its vertical excitation energies but the oscillator strengths vary significantly especially in the case of NKX-2600.
Optical properties of porphyrin analogues for solar cells: An NLO approach
Mannix P. Balanay,Dong Hee Kim 한국물리학회 2011 Current Applied Physics Vol.11 No.1
The geometries, electronic structures, and optical properties of various β-substituted Zn tetraarylporphyrin analogues were studied using density functional theory (DFT). Major differences in geometry and electronic properties were observed as a function of the acceptor moiety. Analogues containing cyanoacrylic acid had longer Zn―N21 bonds, narrower band gaps, and more stabilized energy levels than their methylenemalonic counterparts. Nonlinear optical (NLO) properties were calculated using the Finite Field approach; they were influenced by the strengths of the donor and acceptor moieties and the length of the π-spacer group. The NLO response for all analogues was dominated by only one tensor component, indicating unidirectional charge transfer. The NLO results correlated well with the observed photo-to-current efficiencies provided that the analogues in comparison have the same π-conjugation length.