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Solid‐state dye‐sensitized solar cells employing a solid organic hole‐transport material (HTM) are currently under intensive investigation, since they offer a number of practical advantages over liquid‐electrolyte junction devices. Of particular importance to the design of such devices is the control of interfacial charge transfer. In this paper, the factors that determine the yield of hole transfer at the dye/HTM interface and its correlation with solid‐state‐cell performance are identified. To this end, a series of novel triarylamine type oligomers, varying in molecular weight and mobility, are studied. Transient absorption spectroscopy is used to determine hole‐transfer yields and pore‐penetration characteristics. No correlation between hole mobility and cell performance is observed. However, it is found that the photocurrent is directly proportional to the hole‐transfer yield. This hole‐transfer yield depends on the extent of pore penetration in the dye‐sensitized film as well as on the thermodynamic driving force ΔGdye–HTMfor interfacial charge transfer. Future design of alternative solid‐state HTMs should focus on the optimization of pore‐filling properties and the control of interfacial energetics rather than on increasing material hole mobilities.

The influence of various thermal treatment steps on the morphology and the photoconductive properties of a non‐contacted, 50 nm thick blend (50:50 wt.‐%) of [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) and poly(3‐hexyl thiophene) (P3HT) spin‐coated from chloroform has been studied using transmission electron microscopy (TEM) and the electrodeless time‐resolved microwave conductivity technique. After annealing the film for 5 min at 80 °C, TEM images show the formation of crystalline fibrils of P3HT due to a more ordered packing of the polymer chains. The thermal treatment results in a large increase of the photoconductivity, due to an enhancement of the hole mobility in these crystalline P3HT domains from 0.0056 cm2V–1s–1for the non‐annealed sample to 0.044 cm2V–1s–1for the sample annealed at 80 °C. In contrast, the temporal shape of the photoconductivity, with typical decay half‐times, τ1/2, of 1 μs for the lowest excitation intensities, is unaffected by the temperature treatment. Further annealing of the sample at 130 °C results in the formation of three different substructures within the heterojunction: a PCBM:P3HT blend with PCBM‐rich clusters, a region depleted of PCBM, and large PCBM single crystals. Only a minor increase in the amplitude, but a tenfold rise of the decay time of the photoconductivity, is observed. This is explained by the formation of PCBM‐rich clusters and large PCBM single crystals, resulting in an increased diffusional escape probability for mobile charge carriers and hence reduced recombination.

We have studied the photoinduced charge separation in a double layer consisting of a 50 nm thick, discotic antenna layer, i.e., free‐base tetra‐para‐octylphenyl porphyrin (H2TOPP), spin‐coated onto a smooth layer of anatase TiO2using the electrodeless “flash‐photolysis time‐resolved microwave conductivity” technique (FP‐TRMC). This method enables the investigation of the relationship between the morphology of the antenna layer and the exciton diffusion dynamics. Photons absorbed by the porphyrin result in the formation of free mobile electrons in the conduction band of the TiO2. The freshly spin‐coated double layer shows an incident‐photon‐to‐charge‐separation efficiency (IPCSE) of 10 % on excitation at 430 nm. From the amplitude and the temporal shape of the photoconductivity transients we conclude that for the freshly spin‐coated double layer, electron injection occurs both from the singlet and the long‐lived triplet excited state. These triplet states can travel by (Dexter) energy transfer over distances of at least 9.6 nm. After heating the sample above the crystalline–discotic‐lamellar (C–DL) phase‐transition temperature of H2TOPP and subsequent cooling, changes in the optical absorption spectrum are observed, while the IPCSE drops to ca. 1 %. These results are explained in terms of a transition of the morphology of the antenna layer from a predominantly random distribution of the porphyrin molecules just after spin‐coating to a lamellar arrangement upon annealing, consisting of domains of ordered porphyrin stacks. Since the porphyrin macrocycles are perpendicularly oriented with respect to the plane of the lamellae, the center‐to‐center distance between neighboring lamellae disables efficient triplet energy transfer, leaving only the lamella directly adjacent to the TiO2layer photoactive.

An Eimeria acervulina protein fraction was identified which conferred partial protection against an E. acervulina challenge infection. From this fraction a 37 kDa protein was purified and its corresponding cDNA was cloned and shown to encode a lactate dehydrogenase (LDH). Full length cDNAs encoding LDH from two related species, E. tenella and E. maxima, were also cloned. The homology between the primary amino acid sequences of these three Eimeria LDH enzymes was rather low (66–80%), demonstrating an evolutionary divergence. The Plasmodium LDH crystal structure was used to generate a 3D-model structure of E. tenella LDH, which demonstrated that the many variations in the primary amino acid sequences (P. falciparum LDH and E. tenella LDH show only 47% identity) had not resulted in altered 3D-structures. Only a single LDH gene was identified in Eimeria, which was active as a homotetramer. The protein was present at similar levels throughout different parasitic stages (oocysts, sporozoites, schizonts and merozoites), but its corresponding RNA was only observed in the schizont stage, suggesting that its synthesis is restricted to the intracellular stage.

The degree of adaptation to five concentrations of sucrose was measured. Solutions were kept in the mouth for 25 s; a sweetness judgement was given every 5 s. There were four conditions of mouth movements: no movement, slow, medium and fast mouth movements. It was found that when mouth movements are made there is less adaptation than when there is no mouth movement; however, the rate of movement does not appear to influence the degree of adaptation. Furthermore concentration was found to have an effect. In the no-movement condition, the degree of adaptation seems to rise with concentration, whereas in the movement conditions the opposite effect occurs, i.e. a decrease in the degree of adaptation occurs with increasing sucrose concentration. These phenomena might be explained by the stimulated tongue area, or by taste constancy.