Triphenylamine-based organic sensitizers with pi-spacer structural engineering for dye -sensitized solar cells: Synthesis, theoretical calculations, molecular spectroscopy and structure-property-performance relationships
- Authors
- Eom, Yu Kyung; Hong, Ji Yeoun; Kim, Jeongho; Kim, Hwan Kyu
- Issue Date
- 1월-2017
- Publisher
- ELSEVIER SCI LTD
- Keywords
- pi-Spacers; Triphenylamine; Electron transfer; Intramolecular charge transfer; Structure-property-performance relationships; Dye-sensitized solar cells
- Citation
- DYES AND PIGMENTS, v.136, pp.496 - 504
- Indexed
- SCIE
SCOPUS
- Journal Title
- DYES AND PIGMENTS
- Volume
- 136
- Start Page
- 496
- End Page
- 504
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/85035
- DOI
- 10.1016/j.dyepig.2016.09.007
- ISSN
- 0143-7208
- Abstract
- The heteroaromatic units play a key role in the D-pi-A organic sensitizers for dye-sensitized solar cells (DSSCs), not only as pi-spacers for tuning the optical properties and energy levels, but also as pi-bridges for efficient electron transfer from donor to acceptor unit. The enhancement of pi-spacer donating and accepting abilities is one of essential requirements to improve the molar absorption coefficient and red shift the absorption band in the D-pi-A organic sensitizer, which is beneficial to light harvesting ability. In this study, the effect of pi-spacers in the triphenylamine (TPA)-based sensitizers, such as phenyl, pyridine, thiophene, thienothiophene and benzothiadiazole-thiophene, on photovoltaic performances was systematically investigated. Time-dependent density functional theoretical calculations were also performed to unravel the nature of the absorption induced electronic excitations. Lippert-Mataga analysis shows the characteristics of intramolecular charge transfer on the change of dipole moment to provide a further understanding of charge separation in the organic sensitizer. As the electron richness of pi-spacer is increased, the absorption band and photocurrent density are enhanced in the order of the pi-spacer capability. The DSSC based on TPA-based sensitizer containing thienothiophene exhibits the better power conversion efficiency of 7.40%, J(sc) of 1438 mA cm(-2), V-oc of 694 mV and fill factor of 0.74. These established structure-property-performance relationships give the deep insight on the impact of various pi-spacers in organic sensitizers on device performances and can give molecular design criteria on D-pi-A structured organic sensitizers for high efficiency DSSCs. (C) 2016 Elsevier Ltd. All rights reserved.
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