Coumarin dyes containing low-band-gap chromophores for dye-sensitised solar cells

• Published in: Dyes and pigments Vol. 90; no. 3; pp. 304 - 310
• Main Authors: Seo, Kang Deuk, Song, Hae Min, Lee, Myung Jun, Pastore, Mariachiara, Anselmi, Chiara, De Angelis, Filippo, Nazeeruddin, Mohammad K., Gräetzel, Michael, Kim, Hwan Kyu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-09-2011; Elsevier
• Subjects: Chemical Sciences; Chromophores; Computational efficiency; Computing time; Coumarin; Devices; Dye-sensitised solar cell; Dyes; Ethylenedioxythiophene; Low-band-gap chromophore; Molecular orbitals; or physical chemistry; Photovoltaic cells; Solar cells; Theoretical and; Low-band-gap chromophore; Molecular orbitals; Dye-sensitised solar cell; Coumarin; Ethylenedioxythiophene
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2011.01.009

A series of coumarin dyes containing a low-band-gap chromophore of ethylenedioxythiophene (EDOT), which comprises a coumarin moiety as the electron donor and a cyanoacrylic acid moiety as electron acceptor in D–π–A chromophores, were developed for use in dye-sensitised solar cells (DSSCs). These coumarin dyes have been used to fabricate DSSCs using I
−/I
3
− liquid electrolytes and their device performances were compared with that of
NKX-2677 as a standard dye. Even though
HKK-CM2 and
HKK-CM3 have more extended aromatic units than
HKK-CM1, the degree of π-conjugation in
HKK-CM2 and
HKK-CM3 is less efficient than that of
HKK-CM1, due to the relatively larger torsion angle between the plane of the donor and that of the acceptor. It is also in a good agreement with Density Functional Theory (DFT) calculations. As a result, a solar cell based on
HKK-CM1 sensitiser shows better photovoltaic performance with J
SC of 14.2 mA cm
−2, V
OC of 0.60 V, and a fill factor of 0.70, corresponding to an overall conversion efficiency
η of 6.07% under the standard AM 1.5 irradiation, than
HKK-CM2 and
HKK-CM3-based solar cells.
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► A series of coumarin dyes containing a low-band-gap chromophore (ethylenedioxythiophene), which comprises a coumarin moiety as the electron donor and a cyanoacrylic acid moiety as the electron acceptor in D–π–A chromophores, were developed for use in dye-sensitised solar cells. ► Even though
HKK-CM2 and
HKK-CM3 have more extended aromatic units than
HKK-CM1, the degree of π-conjugation in
HKK-CM2 and
HKK-CM3 is less efficient than that of
HKK-CM1, due to the relatively larger torsion angle between the plane of the donor and that of the acceptor. ► As a result, a solar cell based on
HKK-CM1 sensitiser shows better photovoltaic performance with J
SC of 14.2 mA cm
−2, V
OC of 0.60 V, and a fill factor of 0.70, corresponding to an overall conversion efficiency
η of 6.07% under standard AM 1.5 irradiation, than
HKK-CM2 and
HKK-CM3-based solar cells.