ao7b01195_si_001.pdf (1.82 MB)
Optical and Photovoltaic Properties of Thieno[3,2‑b]thiophene-Based Push–Pull Organic Dyes with Different Anchoring Groups for Dye-Sensitized Solar Cells
journal contribution
posted on 2017-12-29, 09:13 authored by Sara S.
M. Fernandes, M. Cidália R. Castro, Ana Isabel Pereira, Adélio Mendes, Carlos Serpa, João Pina, Licínia L. G. Justino, Hugh D. Burrows, M. Manuela M. RaposoThe
effect of anchoring groups on the optical and electrochemical
properties of triphenylamine-thienothiophenes, and on the photovoltaic
performance of DSSCs photosensitized with the prepared dyes, was studied
using newly synthesized compounds with cyanoacetic acid or rhodanine-3-acetic
acid groups. Precursor aldehydes were synthesized through Suzuki cross-coupling,
whereas Knoevenagel condensation of these with 2-cyanoacetic acid
or rhodanine-3-acetic acid afforded the final
push–pull dyes. A comprehensive photophysical study was performed
in solution and in the solid state. The femtosecond time-resolved
transient absorption spectra for the synthesized dyes were obtained
following photoexcitation in solution and for the dyes adsorbed to
TiO2 mesoporous films. Information on conformation, electronic
structure, and electron distribution was obtained by density functional
theory (DFT) and time-dependent DFT calculations. Triphenylamine–thienothiophene
functionalized with a cyanoacetic acid anchoring group displayed the
highest conversion efficiency (3.68%) as the dye sensitizer in nanocrystalline
TiO2 solar cells. Coadsorption studies were performed for
this dye with the ruthenium-based N719 dye, and they
showed dye power conversion efficiencies enhanced by 20–64%.
The best cell performance obtained with the coadsorbed N719 and cyanoacetic dye showed an efficiency of 6.05%.