Injection Kinetics and Electronic Structure at the N719 TiO2 Interface Studied by Means of Ultrafast XUV Photoemission Spectroscopy

The method of transient XUV photoemission spectroscopy is developed to investigate the ultrafast dynamics of heterogeneous electron transfer at the interface between the N719 ruthenium dye complex and TiO2 nanoparticles. XUV light from high order harmonic generation is used to probe the electron density distribution among the ground and excited states at the interface after its exposure to a pump laser pulse of 530 nm wavelength. A spectral decomposition of the transient emission signal is used to follow the population and decay dynamics of the involved transient states individually. By comparing results obtained for the N719 TiO2 and N719 FTO interfaces, we can unambiguously reveal the kinetics of electrons injected to TiO2 from the singlet metal to ligand charge transfer MLCT excited state of the dye. With the developed approach, we characterize both the kinetic constants and the absolute binding energies of the singlet and triplet MLCT states of the dye and the state of electrons injected to the conduction band of TiO2. The energy levels of the singlet and triplet states are found to lie 0.7 eV above and 0.2 eV below the conduction band minimum, respectively. This energetic structure gives rise to a strong driving force for injection from the singlet state and a slow electron transfer from the triplet state, the latter being possible due to a partial overlap of the triplet state band of N719 and the conduction band of TiO

Improved performance of porphyrin-based dye sensitised solar cells by phosphinic acid surface treatment

Chemical surface treatment of porphyrin-sensitised titania films using bis-(4-methoxyphenyl) phosphinic acid after dye adsorption, results in large improvements in DSSC efficiencies which originate primarily from higher short circuit currents. The result was attributed to a positive shift in the TiO2 quasi-Fermi level with simultaneous retardation of charge recombination. High device performances have been achieved even using simplified electrolyte matrices devoid of the common additives, LiI and t-butylpyridine

1,1′-[(5-Hy­droxy­methyl-1,3-phenyl­ene)bis­(methyl­ene)]dipyridin-4(1H)-one monohydrate

The asymmetric unit of the title compound, C19H18N2O3, comprises a whole organic dipyridinone mol­ecule plus a water mol­ecule of crystallization. The planes of the pyridinone rings are approximately perpendicular with the plane of the central aromatic ring [dihedral angles = 80.68 (8) and 83.65 (8)°]. The C—O bond of the hy­droxy group subtends an angle of 31.71 (10)° with the plane through the central aromatic ring. The crystal packing is mediated by the presence of several O—H⋯O hydrogen-bonding inter­actions and while the water mol­ecules form a C 2 1(4) chain parallel to the c axis of the unit cell, the pendant hy­droxy groups are engaged in O—H⋯O=C hydrogen bonds described by a C 1 1(12) graph-set motif which runs parallel to the a axis

Comprehensive vibrational spectroscopic investigation of trans,trans,trans-[Pt(N3)2(OH)2(py)2], a Pt(IV) diazido anticancer prodrug candidate

We report a detailed study of a promising photoactivatable metal-based anticancer prodrug candidate, trans,trans,trans-[Pt(N3)2(OH)2(py)2] (C1; py = pyridine), using vibrational spectroscopic techniques. Attenuated total reflection Fourier transform infrared (ATR-FTIR), Raman, and synchrotron radiation far-IR (SR-FIR) spectroscopies were applied to obtain highly resolved ligand and Pt-ligand vibrations for C1 and its precursors (trans-[Pt(N3)2(py)2] (C2) and trans-[PtCl2(py)2] (C3)). Distinct IR- and Raman-active vibrational modes were assigned with the aid of density functional theory calculations, and trends in the frequency shifts as a function of changing Pt coordination environment were determined and detailed for the first time. The data provide the ligand and Pt-ligand (azide, hydroxide, pyridine) vibrational signatures for C1 in the mid- and far-IR region, which will provide a basis for the better understanding of the interaction of C1 with biomolecules

Towards hydrogen energy: progress on catalysts for water splitting

This article reviews some of the recent work by fellows and associates of the Australian Research Council Centre of Excellence for Electromaterials Science (ACES) at Monash University and the University of Wollongong, as well as their collaborators, in the field of water oxidation and reduction catalysts. This work is focussed on the production of hydrogen for a hydrogen-based energy technology. Topics include: (1) the role and apparent relevance of the cubane-like structure of the Photosystem II Water Oxidation Complex (PSII-WOC) in non-biological homogeneous and heterogeneous water oxidation catalysts, (2) light-activated conducting polymer catalysts for both water oxidation and reduction, and (3) porphyrin-based light harvesters and catalysts