Chemistry Reference
In-Depth Information
Fig. 7 Fullerene/nickel
porphyrin dyad with a
positive charge located on
the fulleropyrrolidine for
LB and LbL depositions
molecules in adjacent layers influenced the photoresponse. Intermediate ODA
layers were deposited between donor-acceptor layers, and it was estimated that
octadecylamine forced the molecules to a distance of 8
that is still too short for an
Å
optimized solar device.
The possibility to form “directionally” arranged photoactive films is a very
appealing issue for solar organic device, and LB technique is ideal for assembling
highly oriented layers. Particularly, as proposed in many studies [
24
-
29
], the
functionalization of a covalent-bounded fullerene-porphyrin system allows to
assemble molecular wires with a tight spatial alignment. Charvet and coworkers
[
24
] used a substituent with a relatively flat unit with a hydrophilic terminal
triethylene glycol chains, while C
60
acted as a hydrophobic head (Fig.
8
).
Highly efficient photoinduced electron transfer between the porphyrin moiety
and the C
60
was monitored by means of the fluorescence quenching. The photo-
current induced by a white lamp (30 mW/cm
2
illumination flux) was about 15
.
The chemical functionalization in combination with the supramolecular packing
induced by the LB technique leads to build a very promising photoconductive
device.
With this aim, porphyrin-fullerene dyads covalently linked were functionalized
with molecular chains with different properties. Changing the hydrophilic and
hydrophobic features of the attached functionalizations (see Fig.
9a, c
), it is possible
to alternate the orientation of the molecules in opposite directions with respect to
the air-water interface [
25
].
Å
