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Solar cells based on titania require the use of sensitizing dyes in order to make the absorption band coincident with the solar spectrum. The most successful sensitizing dyes are based on Ru-bipyridyls and are chosen for their absorption and redox characteristics. In addition to absorbing visible light, the sensitizing dye injects an electron from its excited state into the band gap of the titania. The injected electron must be conducted through the titania to an electrode upon which the titania is coated. One of the energy wasting pathways available to the injected electron is back transfer to an oxidized dye species on the surface of the titania. We have discovered a simple means of alleviating this energy wasting pathway by anchoring aromatic amines, i.e., co-sensitizers, at low concentration along with the Ru-based bipyridyl sensitizing dye to the surface of titania nanoparticles. Our results indicate that there is a significant increase in cell efficiency (∼15% at AM 1.5, area ≥1 cm2) primarily due to an increase in current when these species are present on the surface in combination with the dyes. We will report our preliminary results on a series of co-sensitizers, and we will compare these to literature findings which use similar compounds as either co-adsorbed species on titania or as substituents on the sensitizing dye molecule itself. [ABSTRACT FROM AUTHOR]

The synthesis of telechelic polyisobutylenes (PIB) by coupling with 2,5-bis-(2-furyl-2-propyl)furan is described. Hydroxyl telechelic PIB with controlled molecular weight was obtained by haloboration-initiation of isobutylene (IB) with a BCl3/BBr3 mixture, followed by coupling of the living ends and oxidation of the (CH3O)2B- end groups with H2O2 in alkaline tetrahydrofuran. Vinyl telechelic PIBs were prepared by coupling living PIB obtained using a novel vinyl functional initiator 5-chloro-3,3,5-trimethyl-1-hexene in conjunction with TiCl4 in hexanes/CH3Cl (60/40, v/v) at -80°C. Chlorosilyl telechelic PIBs were synthesized for the first time by employing chlorosilyl Functional initiators (1-chloro-1-methyl)ethyl-3-(1-dichloro-methylsilyl-methyl)ethylbenzene and 1-methyldichlorosilyl-3,3,5-trimethyl-5-chloro-hexane in conjunction with TiCl4 in hexanes/CH3Cl (60/40, v/v) at -80°C. After coupling, the dichlorosilyl groups were converted to dimethoxysilyl groups upon quenching with methanol. The bis-dimethoxysilyl telechelic PIBs were crosslinked by moisture at room temperature in the presence of catalytic amounts of tin(II) 2-ethyl-hexanoate. Extraction of the crosslinked samples with hexanes resulted in negligible soluble content, indicating essentially quantitative crosslinking. [ABSTRACT FROM AUTHOR]