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Derived from diarylamine sensitizer diphenyl-(7-pyridin-4-yl-9H-carbazol-2-yl)-amine (N13), a series of novel D$-\pi -$A carbazole-based organic dye sensitizers with different $\pi$-linkers were designed for searching more effective sensitizers in dye-sensitized solar cells (DSSCs) design. Optimized geometries, electronic structure, and other parameters, which can evaluate the performance of DSSCs effectively and intuitively, were theoretically calculated by density functional theory (DFT) and time-dependent DFT methods at the M06/6-31G(d,p) level. The results indicated that the maximum absorption wavelength of designed dye was red-shifted and the molar absorption coefficient ($\epsilon$) became higher. This phenomenon can be explained by the modification of the $\pi$-bridge. The simulated Ultraviolet–visible spectroscopy (UV-Vis) absorption spectrum showed that the designed N,N-diphenyl-7-(5-(7-(5-(pyridin-4-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-9H-carbazol-2-amine (N22) dye presents the largest red-shifted absorption band and the designed (E)-N,N-diphenyl-7-(2-(5${}^{\prime }$-(pyridin-4-yl)-[2,2${}^{\prime }$-bithiophene]-5-yl)vinyl)-9H-carbazol-2-amine (N21) dye showed the largest $\epsilon$, both of them depicted a high short-circuit photocurrent density ($J_{\mathrm{\text{sc}}})$. Meanwhile, the charge separation hampered by long $\pi$-linkers was also observed. These results are helpful for designing new sensitizers and providing effective guiding to experimental synthesis.

We are investigating the properties of corrole-sensitized TiO₂ solar cells. The TiO₂-adsorbed free base and Ga^III corroles display cell efficiencies under AM 1.5 illumination that are about half that of a standard N3-sensitized cell (N3 = cis-bis(4,4'-dicarboxy-2,2'-bipyridine)dithiocyanato ruthenium(II)), while that of the Sn^IV-based cell is much lower. The properties of the corrole-TiO₂ solar cells, along with results obtained with electrodes of lower conduction band energies clearly reveal that the reducing power of the singlet excited states of the free base and Ga^III corrole, but not of the Sn^IV derivative, is sufficiently high for efficient injection into the TiO₂ conduction band.

The photophysical properties of toluene solutions of two new 22π expanded porphycene compounds were measured using a combination of various steady-state and time-resolved techniques. The determined triplet energy (E_T= 109 ± 3) kJ.mol^-1, coincident with the calculated E_T = (96.0 ± 10) kJ.mol^-1, of both red absorbing compounds is higher than the energy required to excite ground state molecular oxygen to singlet molecular oxygen. However, the intersystem crossing yield is very low (ca. 10^-2), which makes these compounds poor photosensitizers. The triplet state yield of the two expanded 22π porphyrinoid compounds is much lower than that of the parent porphycene, whereas their fluorescence is as high (ca. 30%) as the value for porphycene. The slower than diffusional quenching rate constant of a porphycene triplet state by the two new compounds reflects a steric hindering factor of the exothermic energy transfer.

A series of porphyrin derivatives with one to four maltohexaose moieties in their meso positions have been synthesized. Zinc or free-base m-THPP (5,10,15,20-tetrakis(m-hydroxyphenyl)-porphyrin) was used as the porphyrin platform. The reaction of m-THPP with 3-iodopropyl nonadecaacetylmaltohexaoside afforded a mixture of all possible combinations of glycoconjugated porphyrins having one to four maltohexaose moieties; monoglycosylated (Ac-1), bisglycosylated (Ac-cis-2 and Ac-trans-2), triglycosylated (Ac-3), and tetraglycosylated (Ac-4) porphyrins were obtained in 11–26% yield. Removal of acetyl groups at maltohexaose moiety afforded highly water-soluble glycoconjugated porphyrins 1–4. Zinc derivatives were synthesized in a similar manner. These maltohexaose-linked porphyrins exhibit remarkable water-solublity (530 mg/mL for 4). The singlet oxygen production ability upon visible light irradiation is not affected by the maltohexaose substitution. Photo- and dark cytotoxicities of the maltohexaose-conjugated porphyrins 1–4 and Zn-1–4 were examined against a HeLa cell line, which showed that the mono-maltohexaosylated derivative (1 and Zn-1) was the most effective photosensitizer for PDT.

In this study, two porphyrin chromophores metallated with ruthenium, RuTBP and RuTBPPy, were prepared and studied as sensitizers in dye-sensitized solar cells (DSSCs). The difference between the two dyes is the position (axial vs. peripheral) of the carboxylic anchoring group. This work examines the impact of this variation towards the optical, electrochemical and photovoltaic performance of DSSCs. The thorough photophysical and photovoltaic measurements indicated that the peripherally substituted sensitizer (RuTBP) presented higher photovoltaic performance compared to RuTBPPy. More specifically, DSSCs sensitized with RuTBP and RuTBPPy displayed an overall power conversion efficiency (PCE) of 5.12% and 4.08%, respectively. The higher PCE value of the DSSC sensitized with RuTBP is mainly attributed to the enhancement of $J_{\mathrm{\text{sc}}}$ and FF values. These factors were enhanced due to the efficient dye regeneration process, the suppression of back-charge recombination reactions and the longer electron lifetimes as evidenced from the electrochemical impedance spectra.

Four asymmetric Zn(II) phthalocyanines (Pc1–Pc4) bearing a carboxylic acid group in the peripheral position have been designed and synthesized to investigate the influence of the distance between COOH group and the phthalocyanine core on their photophysical and photochemical properties. The novel phthalocyanine complexes were characterized by ${}^{\mathrm{\text{1}}}$H, ${}^{\mathrm{\text{13}}}$C NMR, IR, and UV-vis spectroscopies, elemental analysis and matrix-assisted laser desorption ionization mass spectrometry (MALDI). The aggregation behavior, photophysical and photochemical properties such as fluorescence lifetime and quantum yields and singlet oxygen quantum yields of Pc1–Pc4 were explored in tetrahydrofuran (THF) to the determination of the potential use of these novel phthalocyanines as photosensitizers for different applications such as photovoltaic technologies and photodynamic therapy (PDT). Pc1–Pc4exhibited high singlet oxygen generation quantum yields (0.84, 0.66, 0.88 and 0.65, respectively). Fluorescence quantum yields could be obtained for Pc1, Pc2, Pc3 and Pc4 (0.13, 0.31, 0.10 and 0.25, respectively) in THF.