1. Multichromic Supramolecular Dye Architectures for Advanced Light-
Harvesting Applications
Muhammad Yousaf, Mohammad Chaudhry, Muntaser Farooque, Bryan Koivisto*
Science at the Interface Symposium
Wednesday August 19th, 2015
Introduction
Conclusion and Future Work
UV-Vis Spectra
Upon synthesis of the macrocycle, cyclic
voltammetry (CV) and more exhaustive UV-Vis
studies will be performed to show the electronic
properties of the dye in comparison to the
previously synthesised phenylacetylene
macrocycle. The BODIPY core will be substituted
with triphenylamine (TPA) which is strongly
electron donating and cyanoacetic acid a
electron withdrawing group. A device using the
dye will be fabricated, and its efficiency will be
determined.
Figure 5. Spectra of the older moiety (blue) compared to the functionalized
benchmark moiety (orange)
Synthesis
The Device
Dye-synthesized solar cells (DSSCs) have been heavily researched in recent
years due to their low cost of production when compared to classical
silicon based solar devices. DSSCs rely on a redox-active donor (D) linked
through a conjugated π-core substituted with an acceptor (A) which is
capable of anchoring to the TiO2 canvas (Figure 1).1
Acknowledgements
Supramolecular π-spacers
By introducing push-pull functionality into the
macrocyclic portion of the dye, it is theorized that
in the excited state, more electron density will be
pushed towards the core while simultaneously
red shifting the absorbance towards favorable
absorption maxima. This work explores the
synthesis and characterization of a methoxy- and
nitro- substituted phenylacetylene macrocyclic
BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-
indacenes) with comparison to previous work
(Figures 4 & 5).
Figure 4. Previously prepared macrocyclic BODIPY3
(left) and the functionalized phenylacetylene
macrocycle (right)
Figure 3. Excitation energy transfer processes in the absence of
macrocycle (a) and in the presence of macrocycle (b & c); Energy transfers
from macrocycle to DπA dye motif through b) energy transfer (ET) or c)
electron transfer (et).
References
Push-Pull Functionalized Macrocycle
Figure 1. General D-π-A DSSC motif
1. Hagfeldt et al., Chem. Rev. 2010, 110, 6595 - 6663
2. Zhang et al., Angew. Chem. Int. Ed. 2006, 45, 4416 – 4439
3. Yousaf et al. RSC Adv., 2015, 5, 57490–57492
The idea of light-harvesting
supramolecular systems are
not unique, plants utilize
chlorin ring systems in
chlorophyll a and other
pigment molecules to
absorb the Sun’s energy.
Photons can be absorbed by
surrounding pigment and by
resonance transfer be
shuffled to the reaction
center, or the reaction
center can absorb photons
(Figure 2). By combining the
basic DSSC architecture with
that of a large-rigid macrocyclic compound, the possibility of two-photon
absorption exists, one by the core and another by the supramolecule.2 The
appeal of two photon-absorbance is the highly increased absorption
envelope (panchromatic), allowing for more effective devices (Figure 3).
Figure 2. Photosystem I transferring
electrons from antenna pigments towards
the chlorophyll reaction center
We would like to thank
Dr. Bryan Koivisto for all
of his guidance and
support, without whom
this project would not
have been possible. We
would also like to thank
everyone in the
Koivisto group who
each helped us in their
own special way. Lastly, we would like to thank NSERC Canada for their
continued support of this project.