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A Computational and Experimental Study of Thieno[3,4‐b]thiophene as a Proaromatic π‐Bridge in Dye‐Sensitized Solar Cells
Author(s) -
Brogdon Phillip,
Giordano Fabrizio,
Puneky George A.,
Dass Amala,
Zakeeruddin Shaik M.,
Nazeeruddin Mohammad Khaja,
Grätzel Michael,
Tschumper Gregory S.,
Delcamp Jared H.
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201503187
Subject(s) - dye sensitized solar cell , excited state , thiophene , photochemistry , alkyl , materials science , energy conversion efficiency , chemistry , optoelectronics , organic chemistry , atomic physics , electrode , physics , electrolyte
Four D ‐π‐A dyes (D=donor, A=accpetor) based on a 3,4‐thienothiophene π‐bridge were synthesized for use in dye‐sensitized solar cells (DSCs). The proaromatic building block 3,4‐thienothiophene is incorporated to stabilize dye excited‐state oxidation potentials. This lowering of the excited‐state energy levels allows for deeper absorption into the NIR region with relatively low molecular weight dyes. The influence of proaromatic functionality is probed through a computational analysis of optimized bond lengths and nucleus independent chemical shifts (NICS) for both the ground‐ and excited‐ states. To avoid a necessary lowering of the TiO 2 semiconductor conduction band (CB) to promote efficient dye–TiO 2 electron injection, strong donor functionalities based on triaryl‐ and diarylamines are employed in the dye designs to raise both the ground‐ and excited‐state oxidation potentials of the dyes. Solubility, aggregation, and TiO 2 surface protection are addressed by examining an ethylhexyl alkyl chain in comparison to a simple ethyl chain on the 3,4‐thienothiophene bridge. Power conversion efficiencies of up to 7.8 % are observed.