Tuning the Structure and Photophysics of a Fluorous Phthalocyanine Platform.

Phthalocyanines are an important class of industrial dyes with potential commercial applications ranging from photovoltaics to biomedical imaging and therapeutics. We previously demonstrated the versatility of the commercially available zinc(II) hexadecafluorophthalocyanine (ZnF16Pc) as a platform for rapidly developing functional materials for these applications and more. Because this core-platform approach to dye development is increasingly common, it is important to understand the photophysical and structural consequences of the substitution chemistry involved. We present a fundamental study of a series of ZnF16Pc derivatives in which the aromatic fluorine atoms are progressively substituted with thioalkanes. Clear spectroscopic trends are observed as the substituents change from electron-withdrawing to electron-releasing groups. Additionally, there is evidence for significant structural distortion of the normally planar heterocycle, with important ramifications for the photophysics. These results are also correlated to DFT calculations, which show that the orbital energies and symmetries are both important factors for explaining the excited-state dynamics.

Application of solution-processed V2O5 in inverted polymer solar cells based on fluorine-doped tin oxide substrate.

We used a hydrothermal method to synthesis the solution-processed V2O5 as anode buffer layer, which applied on inverted polymer solar cells based on FTO substrate. The structure of the device is glass/FTO/TiO2/P3HT:PCBM/V2O5/Ag. We discussed the dependence of device performance on the concentrations of V2O5 solution. It is found that when the concentration of V2O5 is 300 microg/ml, the power conversion efficiency (PCE of 2.38%) is the highest, which is much higher than that of the device without anode buffer layer (PCE of only 0.87%). Moreover, it can significantly reduce the energy consumption and make it more cost-effective.

Supported F-doped alpha-Fe2O3 nanomaterials: synthesis, characterization and photo-assisted H2 production.

Supported fluorine-doped alpha-Fe2O3 nanomaterials were synthesized by Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) at temperatures between 300 and 500 degrees C, using a fluorinated iron(II) diketonate-diamine compound as a single-source precursor for both Fe and F. The system structure, morphology and composition were thoroughly investigated by various characterization techniques, highlighting the possibility of controlling the fluorine doping level by varying the sole growth temperature. Photocatalytic H2 production from water/ethanol solutions under simulated solar irradiation evidenced promising gas evolution rates, candidating the present PE-CVD approach as a valuable strategy to fabricate highly active supported materials.

A novel liquid plasma AOP device integrating microwaves and ultrasounds and its evaluation in defluorinating perfluorooctanoic acid in aqueous media.

A simplified and energy-saving integrated device consisting of a microwave applicator and an ultrasonic homogenizer has been fabricated to generate liquid plasma in a medium possessing high dielectric factors, for example water. The microwave waveguide and the ultrasonic transducer were interconnected through a tungsten/titanium alloy stick acting both as the microwave antenna and as the horn of the ultrasonic homogenizer. Both microwaves and ultrasonic waves are simultaneously transmitted to the aqueous media through the tungsten tip of the antenna. The microwave discharge liquid plasma was easily generated in solution during ultrasonic cavitation. The simple device was evaluated by carrying out the degradation of the perfluorooctanoic acid (PFOA), a system highly recalcitrant to degradation by conventional advanced oxidation processes (AOPs). PFOA is 59% degraded in an aqueous medium after only 90 s of irradiation by the plasma. Intermediates were identified by electrospray mass spectral techniques in the negative ion mode.

Photochemical decomposition of perfluorooctanoic acid in aqueous periodate with VUV and UV light irradiation.

The photochemical decomposition of perfluorooctanoic acid (PFOA) in aqueous periodate (IO(4)(-)) was investigated under two types of low-pressure mercury lamps: one emits at 254nm light (UV light) and the other emits both 254 nm and 185 nm light (VUV light). PFOA decomposed efficiently under VUV light irradiation while it decomposed poorly under UV light irradiation. The addition of IO(4)(-) significantly increased the rate of decomposition and defluorination of PFOA irradiated with UV light whereas it decreased both processes under VUV irradiation. Reactive radical (IO(3)) generated by photolysis of IO(4)(-) initiated the oxidation of PFOA in UV process. Aquated electrons (e(aq)(-)), generated from water homolysis, scavenged IO(4)(-) resulting in decrease of reactive radical species production and PFOA decomposition. The shorter-chain perfluorocarboxylic acids (PFCAs) formed in a stepwise manner from long-chain PFCAs.

UV waveguides light fabricated in fluoropolymer CYTOP by femtosecond laser direct writing.

We have fabricated optical waveguides inside the UV-transparent polymer, CYTOP, by femtosecond laser direct writing for propagating UV light in biochip applications. Femtosecond laser irradiation is estimated to increase the refractive index of CYTOP by 1.7 x 10(-3) due to partial bond breaking in CYTOP. The waveguide in CYTOP has propagation losses of 0.49, 0.77, and 0.91 dB/cm at wavelengths of 632.8, 355, and 266 nm, respectively.

Rare-earth containing nanocrystal precipitation and up-conversion luminescence in oxyfluoride glasses.

Rare-earth ion doped oxyfluoride glass with a composition of 25SiO2 x 5GeO2 x 15AIO1.5 x 40PbF2 x 10PbO x (4.9 - x)GdF3 x 0.1HoF3 x xYbF3 (x = 0, 0.1,0.2, 0.5,1,2, 3, and 4) in molar ratio was developed. When the oxyfluoride glasses are heat-treated at the first crystallization temperature, the glasses give transparent glass-ceramics in which rare-earth-containing fluorite-type nanocrystals of about 17.2 nm in diameter uniformly precipitated in the glass matrix. Comparing with the glasses before heat treatment, the glass ceramics exhibit very strong up-conversion luminescence under 980-nm light excitation. Rare-earth-containing nanocrystals were also space selectively precipitated upon laser irradiation in an oxyfluoride glass; the size of precipitated nanocrystals can be controlled by laser power and scan speed. The intensity of the green up-conversion luminescence is strongly dependent on the precipitation of beta-PbF2 nanocrystals and the YbF3 concentration. The reasons for the highly efficient Ho3+ up-conversion luminescence are discussed.