This document discusses the use of alkyne functionalized GUMBOS (a new class of tunable materials) as photosensitizing dyes in dye-sensitized solar cells (DSSCs). Rhodamine B-alkyne cation GUMBOS were synthesized with different anions and characterized. Using click chemistry, the alkyne group on the GUMBOS was attached to an azide-terminated linker on a titanium dioxide surface. Future work will involve implementing the GUMBOS in DSSCs.

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Transmittance
Wavenumber (cm-1)
TiO2 TiO2-N3
TiO2-N3-RhB-alk TiO2-N3-RhB-alkBETI
Dye-sensitized solar cells (DSSCs) are relatively
inexpensive photovoltaic cells compared to traditional
silicon-based photovoltaics. Photosensitizing dyes in
DSSCs absorb sunlight and mediate electron transfer
from its excited state to the conduction band of
titanium dioxide. Therefore, attaching photosensitizers
to the surface of the titanium dioxide can yield a more
efficient DSSC. A group of uniform materials based on
organic salts (GUMBOS) and nanoparticles derived
from GUMBOS (nanoGUMBOS) are a new class of
materials that are composed of bulky organic ions, have
a melting point in the range of 25 – 250 °C, and more
recently been evaluated as photosensitizing dyes in
DSSCs. In fact, GUMBOS are of interest since they are
easily functionalized and their properties are tunable
simply by using various cation and anion combinations.
In this study, alkyne functionalized GUMBOS were
synthesized of a rhodamine B-alkyne [Rhb-Alk] cation
and either bis(tri-fluoromethanesulfonyl)imide [NTf2]
anion, or bis(per-fluoroethylsulfonyl)imide [BETI] anion.
The [RhB-Alk][NTf2] and [RhB-Alk][BETI] GUMBOS were
then characterized by ultraviolet-visible absorbance
spectroscopy, fluoresce spectroscopy, and electrospray
ionization mass spectrometry. Finally, using a copper
catalyzed azide-alkyne cycloaddition reaction, known as
click chemistry, the alkyne of the functionalized
GUMBOS was attached to a modified azide terminated
linker on the titanium dioxide surface. Fourier
transform infrared spectroscopy was taken to
characterize the extent of the click reaction.
Synthetic scheme of click reactionAbstract Synthesis of RhB-alkyne and Characterization
Philip W. West Endowment and The National Science
Foundation CHE-1307611. This research is supported in part
by the Department of Energy Office of Science Graduate
Fellowship Program (DOE SCGF), made possible in part
by the American Recovery and Reinvestment Act of 2009,
administered by ORISE-ORAU under contract no. DE-AC05-
06OR23100.
Characterization of the click reaction
Synthesis and characterization of GUMBOS
O NN+
O
O
[RhB-alk]
Cation:
Anions:
Anatomy of DSSC
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Normalizedabsorbance(a.u.)
Wavelength (nm)
10 uM RhB
10 uM RhB-alk
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NormalizedfluorescenceIntensity
Wavelength (nm)
10 uM RhB
10 uM RhB-alk
Absorbance spectra of the RhB and RhB-alkyne in ethanol (a) and corresponding
fluorescence spectra (b).
(a) (b)
Absorbance spectra of the parent dye and the GUMBOS in ethanol (a) and corresponding
fluorescence spectra (b).
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Normalizedabsorbance(a.u.)
Wavelength (nm)
10 uM RhB-alk
10 uM [RhB-alk][BETI]
10 uM [RhB-alk][NTf2]
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Normalizedfluorescenceintensity
Wavelength (nm)
10 uM RhB-alk
10 uM [RhB-alk][BETI]
10 uM [RhB-alk][NTf2]
(a) (b)
Rhb-alk was successfully synthesized as a clickable
GUMBOS.Click chemistry is an acceptable way to attach dyes
with an azide linking group to a TiO2 surface.
Future work includes replication of the click reaction with the
clickable GUMBOS. Implementing the GUMBOS in a DSSC.
Conclusion
Frequency (cm-1) Functional group
2123 N3 Azide stretching
1603 Carboxylate Asymmetric
1417 Aromatic C-C
1289 Carboxylate Symmetric
3200-3500 OH stretch (alcohols)
Stir,
24 hours
+
[Li][NTf2]
in water
[RhB-alk][Cl]
in DCM
[RhB-alk][NTf2]
in DCM
Synthesis of GUMBOS via ion exchange
Application of clickable GUMBOS and nanoGUMBOS as photosensitizers
for use in dye-sensitized solar cells
Dominique D. Beamon, Paulina E. Kolic, Noureen Siraj, and Isiah M. Warner
Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803
Acknowledgements
TiO2 N N+ N- GUMBOS+
TiO2
N
N
N GUMBOS
azide alkyne triazole
CLICK