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Fine Tuning the Performance of DSSCs by Variation of the π‐Spacers in Organic Dyes that Contain a 2,7‐Diaminofluorene Donor
Author(s) -
Baheti Abhishek,
Thomas K. R. Justin,
Lee ChuanPei,
Ho KuoChuan
Publication year - 2012
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201200752
Subject(s) - carbazole , fluorene , photochemistry , thiophene , absorption (acoustics) , acceptor , electron acceptor , homo/lumo , electrochemistry , chemistry , materials science , electron donor , polymer , organic chemistry , catalysis , electrode , molecule , physics , composite material , condensed matter physics
Organic dyes that contain a 2,7‐diaminofluorene‐based donor, a cyanoacrylic‐acid acceptor, and various aromatic conjugation segments, which are composed of benzene, fluorene, carbazole, and thiophene units, as a π‐bridge have been synthesized and characterized by optical, electrochemical, and theoretical investigations. The trends in the absorption and electrochemical properties of these dyes are in accordance with the electron‐donating ability of the conjugating segment. Consequently, the dyes that contained a 2,7‐carbazole unit in the π‐spacer exhibited red‐shifted absorption and lower oxidation potentials than their corresponding fluorene‐ and phenylene‐bridged dyes. However, the enhanced power‐conversion efficiency that was exhibited by the fluorene‐bridged dyes in the DSSCs was attributed to their broader and intense absorption. Despite the longer‐wavelength absorption and reasonable optical density, carbazole‐bridged dyes exhibited lower power‐conversion efficiencies, which were ascribed to the poor alignment of the LUMO level in these dyes, thereby leading to the inhibition of electron injection into the TiO 2 conduction band.