Lee, Min-Woo Kim, Jae-Yup Son, Hae Jung Kim, Jin Young Kim, BongSoo Kim, Honggon Lee, Doh-Kwon Kim, Kyungkon Lee, Duck-Hyung Ko, Min Jae 2024-01-20T08:01:18Z 2024-01-20T08:01:18Z 2021-09-05 2015-01-16 2045-2322 https://pubs.kist.re.kr/handle/201004/125860 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. English NATURE PUBLISHING GROUP SOLID-STATE MOLECULAR DESIGN COUMARIN DYES RECOMBINATION ELECTROLYTE Tailoring of Energy Levels in D-pi-A Organic Dyes via Fluorination of Acceptor Units for Efficient Dye-Sensitized Solar Cells Article 10.1038/srep07711 1 SCIENTIFIC REPORTS, v.5 SCIENTIFIC REPORTS 5 scie scopus 000347902200001 2-s2.0-84946545019 Multidisciplinary Sciences Science & Technology - Other Topics Article SOLID-STATE MOLECULAR DESIGN COUMARIN DYES RECOMBINATION ELECTROLYTE dye-sensitized organic dyes