Photophysics and Nonlinear Absorption of Peripheral-Substituted Zinc Phthalocyanines

Citations Over TimeTop 12% of 2008 papers

Abstract

The photophysical properties, such as the UV-vis absorption spectra, triplet transient difference absorption spectra, triplet excited-state extinction coefficients, quantum yields of the triplet excited state, and lifetimes of the triplet excited state, of 10 novel zinc phthalocyanine derivatives with mono- or tetraperipheral substituents have been systematically investigated in DMSO solution. All these complexes exhibit a wide optical window in the visible spectral range and display long triplet excited-state lifetimes (140-240 mus). It has been found that the complexes with tetrasubstituents at the alpha-positions exhibit a bathochromic shift in their UV-vis absorption spectra, fluorescence spectra, and triplet transient difference absorption spectra and have larger triplet excited-state absorption coefficients. The nonlinear absorption of these complexes has been investigated using the Z-scan technique. It is revealed that all complexes exhibit a strong reverse saturable absorption at 532 nm for nanosecond and picosecond laser pulses. The excited-state absorption cross sections were determined through a theoretical fitting of the experimental data using a five-band model. The complexes with tetrasubstituents at the alpha-positions exhibit larger ratios of triplet excited-state absorption to ground-state absorption cross sections (sigma T/sigma g) than the other complexes. In addition, the wavelength-dependent nonlinear absorption of these complexes was studied in the range of 470-550 nm with picosecond laser pulses. All complexes exhibit reverse saturable absorption in a broad visible spectral range for picosecond laser pulses. Finally, the nonlinear transmission behavior of these complexes for nanosecond laser pulses was demonstrated at 532 nm. All complexes, and especially the four alpha-tetrasubstituted complexes, exhibit stronger reverse saturable absorption than unsubstituted zinc phthalocyanines due to the larger ratio of their excited-state absorption cross sections to their respective ground-state absorption cross sections.

Related Papers

• → Ultrafast Charge-Transfer Dynamics: Studies of p-Nitroaniline in Water and Dioxane(1998)94 cited
• → Charge Separation/Recombination, Intersystem Crossing, and Unusually Slow Intramolecular Triplet–Triplet Energy Transfer in Naphthalenediimide–Anthracene Compact Energy Donor–Acceptor Dyads(2022)16 cited
• → Ultrafast Excited-State Dynamics of 6-Azauracil Studied by Femtosecond Transient Absorption Spectroscopy(2015)15 cited
• → Determination of triplet state intersystem crossing rate constants by microwave induced triplet-triplet absorption in organic molecules(1974)10 cited
• → Theoretical approach to the problem of finding effective luminophors in the isocarbostyril series(1989)2 cited