“…Willner et al investigated the use of β-cyclodextrin-encapsulated dye molecules for the photosensitization of TiO 2 . Other methods have included the structural modification of the dye molecules and the use of inorganic additives. , 1 Participation of Excited Monomer and Aggregate Forms of the Dye Molecule in Sensitizing a Semiconductor Particle…”
The anionic cyanine dye Merocyanine 540 (MC540) dissolved in Aerosol-OT (AOT) solutions of heptane
and toluene possesses a significantly higher fluorescence quantum yield and excited singlet lifetime than the
acetonitrile solutions of the dye. The difference in the photophysical properties observed upon incorporation
of the dye into the AOT micelles is attributed to the decrease in the photoisomerization efficiency. The presence
of AOT also controls the aggregation and photosensitization behavior of MC540 adsorbed onto TiO2
semiconductor nanoparticles. MC540 adsorbed onto nanostructured TiO2 films from acetonitrile solutions
contains both the aggregated and monomeric forms of the sensitizer, while the dye-modified films obtained
from AOT/heptane solutions contain mainly the monomeric form of the sensitizer. Significant enhancement
in the photocurrent generation efficiency has been achieved in photoelectrochemical cells using the AOT
encapsulated dye films. An electroactive polymer (poly(4-vinylpyridine)) film cast on the dye-modified TiO2
electrode has been found to be effective in promoting charge mediation and minimizing dye desorption from
the electrode surface. The incident photon-to-photocurrent generation efficiency (IPCE) exhibited by the
monomeric form (∼40%) is nearly five times greater than the corresponding efficiency of the aggregate form
(∼8%). The beneficial aspects of incorporating dyes in organized assemblies for the purpose of suppressing
nonradiative decay of the excited-state sensitizer and minimizing the aggregation effects on semiconductor
surfaces are discussed.
“…Willner et al investigated the use of β-cyclodextrin-encapsulated dye molecules for the photosensitization of TiO 2 . Other methods have included the structural modification of the dye molecules and the use of inorganic additives. , 1 Participation of Excited Monomer and Aggregate Forms of the Dye Molecule in Sensitizing a Semiconductor Particle…”
The anionic cyanine dye Merocyanine 540 (MC540) dissolved in Aerosol-OT (AOT) solutions of heptane
and toluene possesses a significantly higher fluorescence quantum yield and excited singlet lifetime than the
acetonitrile solutions of the dye. The difference in the photophysical properties observed upon incorporation
of the dye into the AOT micelles is attributed to the decrease in the photoisomerization efficiency. The presence
of AOT also controls the aggregation and photosensitization behavior of MC540 adsorbed onto TiO2
semiconductor nanoparticles. MC540 adsorbed onto nanostructured TiO2 films from acetonitrile solutions
contains both the aggregated and monomeric forms of the sensitizer, while the dye-modified films obtained
from AOT/heptane solutions contain mainly the monomeric form of the sensitizer. Significant enhancement
in the photocurrent generation efficiency has been achieved in photoelectrochemical cells using the AOT
encapsulated dye films. An electroactive polymer (poly(4-vinylpyridine)) film cast on the dye-modified TiO2
electrode has been found to be effective in promoting charge mediation and minimizing dye desorption from
the electrode surface. The incident photon-to-photocurrent generation efficiency (IPCE) exhibited by the
monomeric form (∼40%) is nearly five times greater than the corresponding efficiency of the aggregate form
(∼8%). The beneficial aspects of incorporating dyes in organized assemblies for the purpose of suppressing
nonradiative decay of the excited-state sensitizer and minimizing the aggregation effects on semiconductor
surfaces are discussed.
The embedding of dyes in metal halides, metal sulfides and metal oxides has become possible with the introduction of multi‐source physical vapor deposition (MSPVD). This in turn has led to potential applications such as colored layers, spectral sensitization of semiconductors and systems for controlled release of drugs. The technique of MSPVD is briefly described and the optical properties of the dye composite films are discussed.
Evaporated dye layers are gaining in importance in modern information and energy storage systems due to their specific optical and electrical properties. The photophysical properties decisively depend on the structure of layers, e.g., on a kind of aggregation, degree of crystallinity and crystal modification. These parameters and, therefore, the properties can be strongly manipulated by technological parameters (kind and temperature of substrate, evaporation rate, annealing) and by coevaporated admixtures of inorganic (metal halides or oxides) or organic (dyes or others) compounds.
On the basis of recent investigations of evaporated merocyanine and phthalocyanine dyes, some results of the relationship between deposition are presented technology, structure and photophysical properties and evaluated with regard to their usefulness in organic solar cells.
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