Study of vacuum-evaporated poly(di-methyl silane) thin film and its application to dye-sensitized solar cell
Organopolysilanes are expected to be used for future optical and electronic devices. Poly(di-methyl silane), [Si(CH/sub 3/)/sub 2/]/sub n/, the most fundamental organopolysilane, is not solved in organic solvent at room temperature. Therefore, we have proposed the vacuum evaporation technique in order to obtain thin films of poly(di-methyl silane). In this paper, optical and electrical properties of poly(di-methyl silane) thin films are examined. As a result, it is found that the electric conductivity parallel to the Si backbone is larger by about three orders of magnitude than that perpendicular to the Si backbone. Moreover, highly oriented poly(di-methyl silane) thin film prepared by the vacuum evaporation technique is applied to the dye-sensitized solar cell, and we have succeeded in fabricating the perfectly solid-state dye-sensitized solar cell using poly(di-methyl silane) thin film.
Characteristics ofDye-Sensitized Solar Cells Using Various Dyes
Dye-sensitized solar cells have been fabricated using dyes of ruthenium, NKX-2553, rosehip, blueberry, coffee, and hibiscus, and the characteristics of the dye-sensitized solar cells fabricated have been measured. As a result, it is found that the conversion efficiency of the dye-sensitized solar cell in which ruthenium-dye is used is about 8%, whereas those of the dye-sensitized solar cells in which dyes of rosehip, blueberry, coffee, and hibiscus are used are 0.023, 0.019, 0.015, and 0.015 %, res~(lOCJ7) ly. We have also proposed the perfectly solid-state dye-sensitized solar cell using the poly(dimethyl silane) thin film which is fabricated by the vacuum evaporation technique.
Theoretical study of the effect of substituent and backbone conformation on the electronic properties of symmetrically substituted poly(di‐n‐alkylsilanes)
We present the results of ab initio 3‐21G* geometry optimizations and valence effective Hamiltonian (VEH) band structure calculations aimed at determining the evolution of the geometric and electronic (ionization potential, electron affinities, and band gaps) properties of all‐trans poly(dimethylsilane), poly(diethylsilane), poly(di‐n‐propylsilane), and poly(di‐n‐butylsilane) when increasing the size of the alkyl group. In the latter polymer, we have also studied the 7/3 conformation, in order to analyze the effect of the backbone conformation on the geometric and electronic structure. The VEH ionization potentials of all‐trans poly(di‐n‐alkylsilanes) are almost equal, and as experimental photoemission data show, only slight differences are appreciated. The band gap decreases in going from poly(di‐n‐butylsilane) to poly(di‐n‐propylsilane) and to poly(diethylsilane), and increases when passing to poly(dimethylsilane), which coincides with experimental evidences on poly(di‐n‐alkylsilanes). The change from a...