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Tailoring of Energy Levels in D-pi-A Organic Dyes via Fluorination of Acceptor Units for Efficient Dye-Sensitized Solar Cells

Title
Tailoring of Energy Levels in D-pi-A Organic Dyes via Fluorination of Acceptor Units for Efficient Dye-Sensitized Solar Cells
Authors
Lee, Min-WooKim, Jae-YupSon, Hae JungKim, Jin YoungKim, BongSooKim, HonggonLee, Doh-KwonKim, KyungkonLee, Duck-HyungKo, Min Jae
Ewha Authors
김경곤
SCOPUS Author ID
김경곤scopus
Issue Date
2015
Journal Title
SCIENTIFIC REPORTS
ISSN
2045-2322JCR Link
Citation
SCIENTIFIC REPORTS vol. 5
Publisher
NATURE PUBLISHING GROUP
Indexed
SCI; SCIE; SCOPUS WOS
Document Type
Article
Abstract
A molecular design is presented for tailoring the energy levels in D-pi-A organic dyes through fluorination of their acceptor units, which is aimed at achieving efficient dye-sensitized solar cells (DSSCs). This is achieved by exploiting the chemical structure of common D-pi-A organic dyes and incorporating one or two fluorine atoms at the ortho-positions of the cyanoacetic acid as additional acceptor units. As the number of incorporated fluorine atoms increases, the LUMO energy level of the organic dye is gradually lowered due to the electron-withdrawing effect of fluorine, which ultimately results in a gradual reduction of the HOMO-LUMO energy gap and an improvement in the spectral response. Systematic investigation of the effects of incorporating fluorine on the photovoltaic properties of DSSCs reveals an upshift in the conduction-band potential of the TiO2 electrode during impedance analysis; however, the incorporation of fluorine also results in an increased electron recombination rate, leading to a decrease in the open-circuit voltage (V-oc). Despite this limitation, the conversion efficiency is gradually enhanced as the number of incorporated fluorine atoms is increased, which is attributed to the highly improved spectral response and photocurrent.
DOI
10.1038/srep07711
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자연과학대학 > 화학·나노과학전공 > Journal papers
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