Can elongation of the π-system in triarylamine derived sensitizers with either benzothiadiazole and/or ortho-fluorophenyl moieties enrich their light harvesting efficiency? - A theoretical study

Kadali Chaitanya, Xue Hai Ju, B. Mark Heron

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Abstract

The structural and electronic properties of five known triarylamine derived sensitizers (A1, A1-F, C218, D2 and Y123) and their associated hypothetical dyes (C218-F, D2-F, Y123-F, Y1234 and Y1234-F) have been studied using density functional theory and time-dependent density functional theory. The sensitizers primarily comprise of a triphenylamine, a 4,4′-dihexylcyclopenta[2,1-b:3,4-b]dithiophene and a cyanoacrylic acid as the electron donating, π-spacer and accepting units, respectively. The π-system is extended by incorporation of either a benzo[c][1,2,5]thiadiazol-4,7-diyl unit or an ortho-fluorophenyl unit or both. To gain insight into the effect of elongation of the π-system on the electronic properties of dye sensitized TiO2 interfaces, first-principles calculations have been carried out on sensitizer molecules co-adsorbed on the (101) surface of the anatase TiO2. The theoretical results revealed that elongating the π-system of the sensitizers with both the benzothiadiazole and ortho-fluorophenyl units increases the molecular extinction coefficient, the excited state lifetime and the light harvesting efficiency but decreases the band gap and the reorganization energy relative to the structurally comparable reference dye Y123. The calculated short circuit current density and level alignment quality showed that the π-system in the triarylamine sensitizers elongated with both benzothiadiazole and ortho-fluorophenyl units broadens their potential use in DSSCs due to the enhanced values as compared to the reference dye. The results obtained in this study will provide a valuable reference for the strategy of inserting various π-spacers in triarylamine sensitizers for dye sensitized solar cell applications.

LanguageEnglish
Pages3978-3998
Number of pages21
JournalRSC Advances
Volume5
Issue number6
DOIs
Publication statusPublished - 2015

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Elongation
Coloring Agents
Dyes
Electronic properties
Density functional theory
Excited states
Short circuit currents
Titanium dioxide
Structural properties
Energy gap
Current density
Molecules
Acids
benzo-1,2,3-thiadiazole
Electrons

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title = "Can elongation of the π-system in triarylamine derived sensitizers with either benzothiadiazole and/or ortho-fluorophenyl moieties enrich their light harvesting efficiency? - A theoretical study",
abstract = "The structural and electronic properties of five known triarylamine derived sensitizers (A1, A1-F, C218, D2 and Y123) and their associated hypothetical dyes (C218-F, D2-F, Y123-F, Y1234 and Y1234-F) have been studied using density functional theory and time-dependent density functional theory. The sensitizers primarily comprise of a triphenylamine, a 4,4′-dihexylcyclopenta[2,1-b:3,4-b]dithiophene and a cyanoacrylic acid as the electron donating, π-spacer and accepting units, respectively. The π-system is extended by incorporation of either a benzo[c][1,2,5]thiadiazol-4,7-diyl unit or an ortho-fluorophenyl unit or both. To gain insight into the effect of elongation of the π-system on the electronic properties of dye sensitized TiO2 interfaces, first-principles calculations have been carried out on sensitizer molecules co-adsorbed on the (101) surface of the anatase TiO2. The theoretical results revealed that elongating the π-system of the sensitizers with both the benzothiadiazole and ortho-fluorophenyl units increases the molecular extinction coefficient, the excited state lifetime and the light harvesting efficiency but decreases the band gap and the reorganization energy relative to the structurally comparable reference dye Y123. The calculated short circuit current density and level alignment quality showed that the π-system in the triarylamine sensitizers elongated with both benzothiadiazole and ortho-fluorophenyl units broadens their potential use in DSSCs due to the enhanced values as compared to the reference dye. The results obtained in this study will provide a valuable reference for the strategy of inserting various π-spacers in triarylamine sensitizers for dye sensitized solar cell applications.",
author = "Kadali Chaitanya and Ju, {Xue Hai} and Heron, {B. Mark}",
year = "2015",
doi = "10.1039/c4ra09914a",
language = "English",
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T1 - Can elongation of the π-system in triarylamine derived sensitizers with either benzothiadiazole and/or ortho-fluorophenyl moieties enrich their light harvesting efficiency? - A theoretical study

AU - Chaitanya, Kadali

AU - Ju, Xue Hai

AU - Heron, B. Mark

PY - 2015

Y1 - 2015

N2 - The structural and electronic properties of five known triarylamine derived sensitizers (A1, A1-F, C218, D2 and Y123) and their associated hypothetical dyes (C218-F, D2-F, Y123-F, Y1234 and Y1234-F) have been studied using density functional theory and time-dependent density functional theory. The sensitizers primarily comprise of a triphenylamine, a 4,4′-dihexylcyclopenta[2,1-b:3,4-b]dithiophene and a cyanoacrylic acid as the electron donating, π-spacer and accepting units, respectively. The π-system is extended by incorporation of either a benzo[c][1,2,5]thiadiazol-4,7-diyl unit or an ortho-fluorophenyl unit or both. To gain insight into the effect of elongation of the π-system on the electronic properties of dye sensitized TiO2 interfaces, first-principles calculations have been carried out on sensitizer molecules co-adsorbed on the (101) surface of the anatase TiO2. The theoretical results revealed that elongating the π-system of the sensitizers with both the benzothiadiazole and ortho-fluorophenyl units increases the molecular extinction coefficient, the excited state lifetime and the light harvesting efficiency but decreases the band gap and the reorganization energy relative to the structurally comparable reference dye Y123. The calculated short circuit current density and level alignment quality showed that the π-system in the triarylamine sensitizers elongated with both benzothiadiazole and ortho-fluorophenyl units broadens their potential use in DSSCs due to the enhanced values as compared to the reference dye. The results obtained in this study will provide a valuable reference for the strategy of inserting various π-spacers in triarylamine sensitizers for dye sensitized solar cell applications.

AB - The structural and electronic properties of five known triarylamine derived sensitizers (A1, A1-F, C218, D2 and Y123) and their associated hypothetical dyes (C218-F, D2-F, Y123-F, Y1234 and Y1234-F) have been studied using density functional theory and time-dependent density functional theory. The sensitizers primarily comprise of a triphenylamine, a 4,4′-dihexylcyclopenta[2,1-b:3,4-b]dithiophene and a cyanoacrylic acid as the electron donating, π-spacer and accepting units, respectively. The π-system is extended by incorporation of either a benzo[c][1,2,5]thiadiazol-4,7-diyl unit or an ortho-fluorophenyl unit or both. To gain insight into the effect of elongation of the π-system on the electronic properties of dye sensitized TiO2 interfaces, first-principles calculations have been carried out on sensitizer molecules co-adsorbed on the (101) surface of the anatase TiO2. The theoretical results revealed that elongating the π-system of the sensitizers with both the benzothiadiazole and ortho-fluorophenyl units increases the molecular extinction coefficient, the excited state lifetime and the light harvesting efficiency but decreases the band gap and the reorganization energy relative to the structurally comparable reference dye Y123. The calculated short circuit current density and level alignment quality showed that the π-system in the triarylamine sensitizers elongated with both benzothiadiazole and ortho-fluorophenyl units broadens their potential use in DSSCs due to the enhanced values as compared to the reference dye. The results obtained in this study will provide a valuable reference for the strategy of inserting various π-spacers in triarylamine sensitizers for dye sensitized solar cell applications.

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U2 - 10.1039/c4ra09914a

DO - 10.1039/c4ra09914a

M3 - Article

VL - 5

SP - 3978

EP - 3998

JO - RSC Advances

T2 - RSC Advances

JF - RSC Advances

SN - 2046-2069

IS - 6

ER -