An Acetylacetonate-Based Semiconductor−Sensitizer Linkage

Abstract

Coordination compounds of the general type Ru(dmb)2(LL)(PF6)2, where dmb is 4,4‘-(CH3)2-2,2‘-bipyridine and LL is 4-(CH3)-4‘-(COOH)-2,2‘-bipyridine, or 4-(CH3)-4‘-((CH2)3COOH)-2,2‘-bipyridine, or 4-(CH3)-4‘-((CH2)3COCH2COOC2H5)-2,2‘-bipyridine were prepared for the attachment to semiconductor metal oxide surfaces. The optical and redox properties of these compounds in dichloromethane solution are reported. Binding to porous nanostructured TiO2 films was analyzed with the Langmuir adsorption isotherm model. Photoelectrochemical measurements of the modified TiO2 electrodes in regenerative solar cells are reported. The results indicate that intimate electronic coupling between the surface link and the chromophoric ligand is not a strict requirement in the design of sensitizers for photovoltaic applications. Interfacial kinetics for recombination of the electron in the solid with the oxidized form of the sensitizer were quantitated by excited state absorption spectroscopy.

Electron Injection, Recombination, and Halide Oxidation Dynamics at Dye-Sensitized Metal Oxide Interfaces

“…5 Insulating ZrO 2 films were prepared from Zr(i-OPr) 4 in a similar fashion. 6 Transparent SnO 2 films were prepared using a slight modification of a published procedure: 7 One drop of Triton X-100 surfactant was added to 1 mL of 15% SnO 2 colloidal solution (Alfa). This mixture was deposited on the substrate and spread with a glass rod over an area masked with Scotch tape.…”

Photoconductive ZnO films with embedded quantum dot or ruthenium dye sensitizers

“…Remarkably, even [Ru(bpy) 3 ] 2+ sensitizes ZnO to visible light effectively, despite the absence of coordinating functional groups (e.g., carboxylates) on the bipyridyl ligands, illustrating the phenomenon of "remote" interfacial electron transfer identified in dye sensitized solar cells lacking intimate electronic coupling between the chromophore and the oxide surface. 20,21 Photoinduced electron transfer from quantum dots to n-type oxide semiconductors through hydrocarbon spacers is also well documented. 8,22 We note that the first excitonic absorption feature of each QD sample is shifted to slightly lower energy (by <20 meV) relative to colloidal suspensions of the same QDs, possibly due to relaxation of the photoexcited electron's wavefunction into the surrounding ZnO matrix.…”

Development of a New System for Photocatalytic Water Splitting into H2 and O2 under Visible Light Irradiation

“…Since these dyes are barely soluble in an aqueous solution with a neutral pH, the CV measurements were carried out using nanoporous TiO 2 electrodes with the dyes adsorbed on them. 184 In all cases, a current peak was observed when an anodic potential of over +0.4 V (vs. reference) was applied, which indicates oxidation of the dye molecule (S) to an oxidized state (S + ). On the other hand, the reduction behavior strongly depended on the structure of the dye molecule.…”