Porphyrin Dye-Sensitized Zinc Oxide Aggregated Anodes for Use in Solar Cells

Tetracationic porphyrin derivatives against human breast cancer

Photodynamic therapy (PDT) is an approved therapeutic approach and an alternative to conventional chemotherapy for the treatment of several types of cancer with the advantages of reducing the side effects and developing resistance mechanisms. Here, was evaluated the photosensitization capabilities of 5,10,15,20-tetrakis[4-(pyridinium-1-yl-methyl)phenyl]porphyrin (3), its N-confused isomer (4) and of the neutral precursors (1) and (2) and the results were compared with the ones obtained with the cationic 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP). Both regular porphyrin derivatives 1 and 3 showed higher efficiency to generate singlet oxygen than TMPyP. The PDT assays towards MCF-7 cells under red light irradiation (λ > 640 nm, 23.7 mW cm^-2) demonstrated that the cationic porphyrin 3 is an efficient photosensitizer to kill MCF-7 breast cancer cells. The study of the cell death mechanisms induced by the photodynamic process showed that the studied porphyrin 3 and TMPyP caused cell death by autophagic flux and necrosis.

Improved Performance of Dye-Sensitized Solar Cells with TiO2 Nanoparticles/Zn-Doped TiO2 Hollow Fiber Photoanodes

In this study, dye-sensitized solar cells (DSSCs) were fabricated using double-layer photoanodes consisting of TiO2 nanoparticles (NPs) and Zn-doped TiO2 hollow fibers (HFs). The TiO2 HFs were prepared by co-axial electrospinning and used as the light-scattering layer in the DSSC. The thickness variations of the TiO2 NP and Zn-doped TiO2 HF photoanode layers affect the performance of the DSSC, especially the short-circuit photocurrent density. The thickness of the TiO2 NP layer significantly affected the absorbance of photons and N719 dye molecules in the double-layer photoanode, while that of the Zn-doped TiO2 HF layer affected the scattering of light, as indicated by the low light transmittance in the photoanode. Conventional DSSCs consist of single-layer photoanodes, and exhibit relatively low efficiency, i.e., 1.293% and 0.89% for TiO2 NP and Zn-doped TiO2 HF, respectively. However, herein, the highest efficiency of the DSSC (3.122%) was achieved with a 15 μm NP-5 μm HF photoanode, for which the short-circuit photocurrent density, open-circuit photovoltage, and fill factor were 15.81 mA/cm2, 0.566 V, and 34.91%, respectively.

N-Confused Porphyrin Immobilized on Solid Supports: Synthesis and Metal Ions Sensing Efficacy

In this work, the N-confused porphyrin 5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrin (NCTPP) was immobilized on neutral or cationic supports based on silica and on Merrifield resin. The new materials were characterized by appropriate techniques (UV-Vis spectroscopy, SEM, and zeta potential analysis). Piezoelectric quartz crystal gold electrodes were coated with the different hybrids and their ability to interact with heavy metals was evaluated. The preliminary results obtained showed that the new materials can be explored for metal cations detection and the modification of the material surface is a key factor in tuning the metal selectivity.

Efficient Dye-Sensitized Solar Cells Based on Nanoflower-like ZnO Photoelectrode

A photoanode material ZnO nanoflower (ZNFs) for efficient dye-sensitized solar cell (DSSC) was prepared. This unique structure can significantly increase the specific surface area and amount of light absorption, leading to a higher short-circuit current density. Furthermore, ZNFs resulted in closer spacing between the nanorods and more direct conduction paths for electrons, leading to higher open-circuit voltage. The overall promising power conversion efficiency of 5.96% was obtained with photoanodes of 8.5 μm thickness. This work shows that ZNFs is an attractive material and has good potential for application in high efficiency ZnO-based DSSCs.