The importance of non-radiative processes in porphyrins and phthalocyanines for photocurrent generation study

Control of Molecular Energy Redistribution Pathways via Surface Plasmon Gating

“…Well-known examples include isomerization of the retinal rhodopsin for optical signal transduction [1], or light harvesting energy transfer via dipole-dipole coupling in photosynthetic reaction centers [2]. Molecular electronic energy redistribution also impacts important high technology issues, such as excited state deactivation responsible for reduced energy conversion efficiencies in solar cells [3], isomerization for molecular electronics and molecular optics applications [4], and the efficiencies of organic light emitting diodes [5]. In many cases, energy redistribution consists of competing processes that fundamentally limit the efficiency of a desired pathway following photoexcitation, such as charge separation, bond breakage, or luminescence.…”

Charge transfer in fullerene – porphyrin-derived dyads studied with light-induced electron spin resonance

“…3) with the light switching off, as well as the g-factor and linewidth values testify the LESR signal origin-it is given by excited porphyrins moieties in their triplet states. In porphyrins population of the triplet states generated due to intersystem crossing and evaluated on the basis of the time resolved photothermal spectroscopy is high; from about 0.5 to 0.8 depending on dye, substituents and solvent [41]. Also the lifetime of the porphyrins triplet states are depending on the substituents, but usually they are of the order of ls [42,43].…”

Triplet Thermal Relaxation Study as a Probe of Weak Interdimers of Porphyrin Derivatives

“…The Φ F values of samples 3 and 5 in water are ∼0.005 and 0.03, respectively, and they are higher in dioxane (up 0.09) [26,52]. Shortening of τ N is also noticed ( the values of the natural life time of the investigated porphyrin samples versus τ N of zinc tetraphenylporphyrin) in DMSO (25 ns) [53,56]. There could be at least three reasons for the observed changes in the fluorescence parameters: solvent polarity effect and aggregate formation as well as the presence of PEG [23].…”

“…Thus, we will not discuss this problem, but rather we focus our study mostly on the influence of the solvent polarity on interactions between the dye molecules. The absorption band's locations and the values of the half-widths of the maxima of the samples in dioxane (solvent of low polarity) are as observed for porphyrin monomeric species in other organic solvents [52][53][54][55][56].…”

“…The changes of the band positions of the samples in DMSO with respect to those in the remaining solvents [23] can be assigned to differences in electrical susceptibilities of DMSO and dioxane and in universal interactions between the dye and solvent. Moreover, the values of the fluorescence band intensity ratios (FR in Table 1 [53,56] could be assigned to overlapping contributions of intramolecular charge transfer and interactions in molecular aggregates, e.g., processes that could lead to modification of the singlet-triplet transition in chromophores.…”