Anchoring Group and π-Spacer Effects on the Dynamics and Kinetics of the Photovoltaic Processes in the Quinoxaline-Based Organic Dye-Sensitized Solar Cells

Int J of Quantum Chemistry

2020

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The molecular modification and the effects of the gas and water media on the ability of some flavonoids as the photosensitizers in the natural dye‐sensitized solar cells were theoretically investigated. According to the results, water increases the electrophilicity of the dyes and weakens the dye/TiO2 coupling, prohibiting the electron injection toward TiO2. A longer path for charge transfer and a less electron‐hole overlap for dihydroxychromens elevate the electron transfer more efficient than trihydroxychromen‐based flavonoids. However, the presence of water molecules within an increment in the OH groups in the flavonoid structures improves their spectroscopic properties, which is related to decrement in the gap of the frontier molecular orbitals and increment in the oscillator strength. Also, such favorable structural effects and influence of the water medium on the polarizability and excited‐state lifetime have emerged. According to the energy conversion efficiency, water is a favorable solvent for dihydroxychromen‐based flavonoids. Finally, different analyses on the structural geometries, excited‐state, lifetime within the kinetics, and dynamics of the photovoltaic processes were performed and discussed.

{EBE}^{S} = \frac{{(α_{C / e} - 1)}^{2} μ_{x} e^{4} k^{2}}{2 {α_{C / e}}^{2} ћ^{2} ε^{2}}

Section: Computational Detailsmentioning

confidence: 99%

“…To calculate the exciton radius in the photosensitizers, the value of the material-dependent constant, α C/e , which shows the ratio of the Coulomb/exchange interactions between the excited electron and hole is required that is obtained by Equation (5): [37]…”

Section: Computational Detailsmentioning

confidence: 99%

Photovoltaic properties of the flavonoid‐based photosensitizers: Molecular‐scale perspective on the natural dye solar cells

Int J of Quantum Chemistry

2020

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“…Electron injection from the excited states of the dye to the TiO 2 surface, Δ G inj. , is given by Equation ) [ 31 ] :

normalΔ G_{inj .} = E_{OX, dye *} - E_{CB ()(, {TiO}_{2})}

where

E_{CB ()(, {TiO}_{2})}

is the conduction band energy of TiO 2 , and E OX,dye* is the excited state oxidation potential of the photosensitizer. The driving force of the electron transfer from the photosensitizer toward semiconductor, eV OC , is derived from Equation ) [ 32 ] :

{eV}_{OC} = E_{LUMO ()(, dye)} - E_{CB ()(, Ti O_{2})}

…”

Section: Computational Detailsmentioning

confidence: 99%

“…Electron injection from the excited states of the dye to the TiO 2 surface, ΔG inj. , is given by Equation (3) [31] :…”

Section: Computational Detailsmentioning

confidence: 99%

Insight into incident photon to current conversion efficiency in chlorophylls

Int J of Quantum Chemistry

2020

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Photovoltaic properties of the natural dyes of chlorophylls consist ofChl a,Chl b,Chl c2,Chl d,Phe a,Phe y, andMg‐Phe aand have been studied in the gas phases and water. The extension of the π‐conjugated system, the substitution of the central Mg2+, and proper functional groups in the chlorophyll structures can amplify the charge transfer and photovoltaic performance.Chl ashows more favorable dynamics of charge transfer than the other studied chlorophylls.Chl d,Phe a,Phe y, andMg‐Phe ahave a greater rate of exciton dissociation in comparison withChl a,Chl b, andChl c2originating from a lower electronic chemical hardness, a lower exciton binding energy, and a bigger electron‐hole radius. As a result, better efficiencies of light harvesting and energy conversion of the chlorophylls mainly appear in the Soret band. The light‐harvesting efficiency values of the chlorophylls in water show that solvent favorably affects the ability of light harvesting of the photosensitizers. Finally, based on the energy conversion efficiency,Chl a,Phe a, andMg‐Phe aare proposed as the best candidates for use in the dye‐sensitized solar cells.

“…Electron injection from the excited states of the dye to the TiO 2 surface, ΔΓ ινθ. , is given by Equation (3) [28] :…”

Section: Computational Detailsmentioning

confidence: 99%

Insight into incident photon to current conversion efficiency in chlorophylls

2020

Preprint

Self Cite

Photovoltaic properties of the natural dyes of chlorophylls consist of Chl a, Chl b, Chl c2, Chl d, Phe a, Phe y and Mg-Phe a, were studied in the gas phases. The extension of the π-conjugated system, the substitution of the central Mg2+ and proper functional groups in the chlorophyll structures can amplify the charge transfer and photovoltaic performance. Chl a shows more favorable dynamics of charge transfer than other studied chlorophylls. Chl d, Phe a, Phe y and Mg-Phe a, have a greater rate of the exciton dissociation in comparison with Chl a, Chl b, and Chl c2 originated from a lower electronic chemical hardness, a lower exciton binding energy, and a bigger electron-hole radius. As a result, better efficiencies of the light-harvesting and energy conversion of the chlorophylls mainly appear in the Soret band. Finally, based on the energy conversion efficiency, Chl a, Phe a, and Mg-Phe a, are proposed as the best candidates for using in the dye-sensitized solar cells.