It is connected with an exciton short lifetime (order of picoseconds) and leads to
fast charge recombination. Thus, searching for new systems which are able to omit
or reduce above problems seems to be very essential. To get knowledge on physical
and photophysical properties, the following research techniques are mostly used:
UV-VIS, IR absorption, FT-IR spectroscopy, in situ absorption spectroscopy,
fluorescence spectroscopy, electron paramagnetic resonance (EPR) spectroscopy,
thin film, and computer simulations.
3.4 Phthalocyanine and Porphyrin with Quantum Dots
For many reasons, organic photoactive systems composed with organic dyes and
semiconductor quantum dot are of a wide interest among many researchers due to
their perspective applications [32–38]. Phthalocyanines with a quantum dot are
more complex systems than those discussed above.
The process responsible for that was described as the fluorescence resonance
energy transfer. There are some examples of that. In CdTe-sulfonated aluminum
phthalocyanines systems, the QD can be used as a perfect energy donor to
phthalocyanine after light excitation. In the QD-organic dye system, phthalocyanines play a role of photosensitizers [33, 34]. The studies in the paper [37] on the
cell with QD and semiconducting polymer (PCPDTBT) evidently showed the
enhancement of the short-circuit current and that the blend of spherical quantum
dots and elongated nanorods results in a good electron pathway in the p-polymer
matrix, giving efficiencies of 3.6%. What is worth to underline is how fabrication
methods of the quantum dots, morphology of the photoanode, the type of electrolyte used, and the choice of the counter electrode can improve solar cell efficiencies [36].
Spectroscopic and thermodynamic examinations of dyes are one of the steps
allowing determination of the mechanisms of interrelation, aggregation, and electron transfer processes. Models composed of QD and chromophores in solution as
well as in the Langmuir layer can be an example which gives a description of the
interaction between units.
The core/shell CdSe/ZnS QD and structurally different zinc(II) and copper(II)
phthalocyanines substituted with butyl or octakis(octyloxy) peripheral groups
(2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine 2,3,9,10,16,17,23,24-octakis
(octyloxy)-29H,31H-phthalocyanine) and indium and gal phthalocyanines are
excellent models to be investigated. Figure 3.2 presents absorption spectra of zinc
phthalocyanine in solution (Fig. 3.2a), creation of aggregates with the use of in situ
Langmuir layer (Fig. 3.2b), p-A isotherm (Fig. 3.2c) and compressibility of the dye
layer (Fig. 3.2d). Compression modulus of the layers evaluated with the use of a
Langmuir trough lets to determine their thermodynamic properties. The following
parameters can be estimated: p-A compression isotherms (compression versus
molecule area), compression-collapse parameters, and stability of layers. These
3 Quantum Dot and Fullerene with Organic Chromophores as …
103
fast charge recombination. Thus, searching for new systems which are able to omit
or reduce above problems seems to be very essential. To get knowledge on physical
and photophysical properties, the following research techniques are mostly used:
UV-VIS, IR absorption, FT-IR spectroscopy, in situ absorption spectroscopy,
fluorescence spectroscopy, electron paramagnetic resonance (EPR) spectroscopy,
thin film, and computer simulations.
3.4 Phthalocyanine and Porphyrin with Quantum Dots
For many reasons, organic photoactive systems composed with organic dyes and
semiconductor quantum dot are of a wide interest among many researchers due to
their perspective applications [32–38]. Phthalocyanines with a quantum dot are
more complex systems than those discussed above.
The process responsible for that was described as the fluorescence resonance
energy transfer. There are some examples of that. In CdTe-sulfonated aluminum
phthalocyanines systems, the QD can be used as a perfect energy donor to
phthalocyanine after light excitation. In the QD-organic dye system, phthalocyanines play a role of photosensitizers [33, 34]. The studies in the paper [37] on the
cell with QD and semiconducting polymer (PCPDTBT) evidently showed the
enhancement of the short-circuit current and that the blend of spherical quantum
dots and elongated nanorods results in a good electron pathway in the p-polymer
matrix, giving efficiencies of 3.6%. What is worth to underline is how fabrication
methods of the quantum dots, morphology of the photoanode, the type of electrolyte used, and the choice of the counter electrode can improve solar cell efficiencies [36].
Spectroscopic and thermodynamic examinations of dyes are one of the steps
allowing determination of the mechanisms of interrelation, aggregation, and electron transfer processes. Models composed of QD and chromophores in solution as
well as in the Langmuir layer can be an example which gives a description of the
interaction between units.
The core/shell CdSe/ZnS QD and structurally different zinc(II) and copper(II)
phthalocyanines substituted with butyl or octakis(octyloxy) peripheral groups
(2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine 2,3,9,10,16,17,23,24-octakis
(octyloxy)-29H,31H-phthalocyanine) and indium and gal phthalocyanines are
excellent models to be investigated. Figure 3.2 presents absorption spectra of zinc
phthalocyanine in solution (Fig. 3.2a), creation of aggregates with the use of in situ
Langmuir layer (Fig. 3.2b), p-A isotherm (Fig. 3.2c) and compressibility of the dye
layer (Fig. 3.2d). Compression modulus of the layers evaluated with the use of a
Langmuir trough lets to determine their thermodynamic properties. The following
parameters can be estimated: p-A compression isotherms (compression versus
molecule area), compression-collapse parameters, and stability of layers. These
3 Quantum Dot and Fullerene with Organic Chromophores as …
103