phthalocyanine macroring on dye thermodynamic properties is presented in [19]; the
creation of the H aggregate in GaPc or oblige in InPc (the later not shown). The in situ
studies clearly confirmed the significant influence of metal in the indium, gallium, or
zinc phthalocyanine macroring and the kind of aggregates [19]. The absorption spectra
and the in situ study of the Langmuir monolayer were also done for
copper(II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine, copper(II) 2,3,9,10,
16,17,23,24-octakis(octyloxy)-29H31H-phthalocyanine,
zinc(II))2,9,16,23-tetratert-butyl-29H,31H-phthalocyanine, and zinc(II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H31H-phthalocyanine with QD. The in situ absorption spectra in the Q region
are characterized by clear two maxima—the result indicates the exciton energy splitting
and the presence of aggregates. The models composed of QD and chromophores in
solution as well as in the 2D Langmuir monolayers can be an example which gives
description of the interaction between an organic chromophore and a semiconductor
dot.
The correlation of the in situ spectra and electronic absorption spectra confirms
(or excludes) formation of molecular aggregates. When one compares the electronic
spectrum in chloroform with the in situ curves, it is evident that the existence of dye
aggregates in the monolayer can be observed. Investigations of thin layers are
extremely useful for determining such values as the compressibility and stability of
the layers that are important for optoelectronics. Besides, it is interesting that
quantum dots in Langmuir’s two-dimensional layers can significantly reduce the
formation of molecular aggregates [39, 40]. Moreover, it is also worth emphasizing
that orientation of the molecules is one of the most important factors that affect the
efficiency of the energy transfer process. For this reason, investigations of the dye
layers are essential to get knowledge on arrangement of the molecular skeleton
which influences electron transfer [39].
The photoinduced single-step electron transfer in the systems based on organics
and QD is of a great interest and is presented in many papers [41–44]. As said
above, the systems based on metallic phthalocyanine with QD is one of interesting
examples of electro-donor-acceptor mixture. The spectroscopic experiments of zinc
and copper phthalocyanines substituted with tetrabutyl side groups (ZnPc-tetr,
Cu-tetr) and octyloxy groups (ZnPc-octy, CuPc-octy), their mixtures with CdSe/
ZnS quantum dots in chloroform are a proof of creation of the efficient
donor-acceptor systems. Interaction between the phthalocyanine dye and CdSe/ZnS
quantum dot observed as dot fluorescence quenching is shown in Fig. 3.3.
The spectra show fluorescence of QD (max 585 nm) and its quenching with the
rising concentration of Pc resulting in energy transfer from QD to Pc. The influence
of the substituent attached to the phthalocyanine macroring and of the presence of
the quantum dot fluorescence is evident—the value of energy transfer yield (U ET )
can reach up to 70–90% [20]. The Pc-QD system fulfills one of the important
conditions of the non-radiative resonance energy transfer (Fӧrster model—FRED)
between isolated D and A—overlapping of the donor emission with absorption
spectra of acceptor [20]. Confirmation of the photoinduced single-step electron
transfer on the nanometer scale in systems like strongly coupled zinc
3 Quantum Dot and Fullerene with Organic Chromophores as …
105
creation of the H aggregate in GaPc or oblige in InPc (the later not shown). The in situ
studies clearly confirmed the significant influence of metal in the indium, gallium, or
zinc phthalocyanine macroring and the kind of aggregates [19]. The absorption spectra
and the in situ study of the Langmuir monolayer were also done for
copper(II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine, copper(II) 2,3,9,10,
16,17,23,24-octakis(octyloxy)-29H31H-phthalocyanine,
zinc(II))2,9,16,23-tetratert-butyl-29H,31H-phthalocyanine, and zinc(II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H31H-phthalocyanine with QD. The in situ absorption spectra in the Q region
are characterized by clear two maxima—the result indicates the exciton energy splitting
and the presence of aggregates. The models composed of QD and chromophores in
solution as well as in the 2D Langmuir monolayers can be an example which gives
description of the interaction between an organic chromophore and a semiconductor
dot.
The correlation of the in situ spectra and electronic absorption spectra confirms
(or excludes) formation of molecular aggregates. When one compares the electronic
spectrum in chloroform with the in situ curves, it is evident that the existence of dye
aggregates in the monolayer can be observed. Investigations of thin layers are
extremely useful for determining such values as the compressibility and stability of
the layers that are important for optoelectronics. Besides, it is interesting that
quantum dots in Langmuir’s two-dimensional layers can significantly reduce the
formation of molecular aggregates [39, 40]. Moreover, it is also worth emphasizing
that orientation of the molecules is one of the most important factors that affect the
efficiency of the energy transfer process. For this reason, investigations of the dye
layers are essential to get knowledge on arrangement of the molecular skeleton
which influences electron transfer [39].
The photoinduced single-step electron transfer in the systems based on organics
and QD is of a great interest and is presented in many papers [41–44]. As said
above, the systems based on metallic phthalocyanine with QD is one of interesting
examples of electro-donor-acceptor mixture. The spectroscopic experiments of zinc
and copper phthalocyanines substituted with tetrabutyl side groups (ZnPc-tetr,
Cu-tetr) and octyloxy groups (ZnPc-octy, CuPc-octy), their mixtures with CdSe/
ZnS quantum dots in chloroform are a proof of creation of the efficient
donor-acceptor systems. Interaction between the phthalocyanine dye and CdSe/ZnS
quantum dot observed as dot fluorescence quenching is shown in Fig. 3.3.
The spectra show fluorescence of QD (max 585 nm) and its quenching with the
rising concentration of Pc resulting in energy transfer from QD to Pc. The influence
of the substituent attached to the phthalocyanine macroring and of the presence of
the quantum dot fluorescence is evident—the value of energy transfer yield (U ET )
can reach up to 70–90% [20]. The Pc-QD system fulfills one of the important
conditions of the non-radiative resonance energy transfer (Fӧrster model—FRED)
between isolated D and A—overlapping of the donor emission with absorption
spectra of acceptor [20]. Confirmation of the photoinduced single-step electron
transfer on the nanometer scale in systems like strongly coupled zinc
3 Quantum Dot and Fullerene with Organic Chromophores as …
105