| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2002: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
[1]Sensitization effect of porphyrin dye on photocurrent of Al/polythiophene Schottky-barrier cells
We prepared organic solar cells consisting of a blend of soluble conjugated polymer as better charge-transport material and dye as more effective light-harvesting material. We clarified the photocurrent enhancement in the Al/P3HT+porphyrin Schottky-barrier solar cell and the enhanced mechanism, where P3HT is a regioregular polythiophene. Various porphyrins with different substituents were employed in the cell to examine which factors are dominant for the photocurrent enhancement. The photocurrent for irradiation from the Al side was much larger for the blend cell of porphyrin+P3HT than for the pure cell of porphyrin or P3HT. The photo-charge separation mainly occurred in the narrow region of about 15 nm of organic solid side at the Al/organic solid interfaces, where the electric field was as large as 10^5 Vcm^<-1>. That is, photons absorbed in the narrow organic solid layer which has the
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potential gradient were effectively used for the photocurrent generation. However, the observed photocurrent enhancement was not attributed to the magnitude o」 the electric field at the Al/organic solid interface, but to the ease of the photoinduced hole-transfer from porphyrin to P3HT. That is, when the thermodynamic driving force of the hole-transfer was large and the distance between conjugated planes of porphyrin and P3HT was short, remarkable photocurrent enhancement was observed.
[2]Photocurrent enhancement in TiO_2/polythiophene+merocyanine/Au solid-state solar cells
A solar cell consisting of a transparent and flat, that is, non-porous TiO_2 film as the electron-transporting layer and a conjugated regioregular polythiophene as the hole-transporting layer was investigated. When a merocyanine dye was blended into the regioregular polythiophene (P3HT) in the TiO_2/P3HT/Au sandwich-type solar cell, the cell performance was remarkably enhanced, resulting in 0.32 % of energy conversion yield under the irradiation of AM1.5-100mWcm^<-2>. Further, the photo-voltaic mechanism was discussed on the base of the energy level diagram of the component materials before contact and so-called an optical filtering effect of the photocurrent. The depletion layer for the photo-charge separation lies in the blended solid side at the TiO_2/merocyanine+P3HT interface, and the film thickness of more than 40nm is estimated as the region.
[3]Performance enhancement by blending an electron acceptor in TiO_2/polyphenylenevinylene/Au solid-state solar cells
A solar cell consisting of a transparent and flat, that is, non-porous TiO_2 film as an n-type semiconductor and a conjugated polymer MEH-PPV as a p-type semiconductor was investigated. When [2-[2-[4-(dimethylamino)phenyl]ethenyl]-6-methyl-4H-pyran-4-ylidene]propanedinitrile (DCM) as an electron acceptor was blended into poly[2-methoxy-5-(2'-ethylenehexyloxy)-1,4-phenylenevinylene (MEH-PPV) as a donor in the TiO_2/MEH-PPV/Au sandwich-type solar cell, the cell performance was remarkably enhanced. After all, the energy conversion yield resulted in 0.47 % under the irradiation of AM1.5-100mWcm^<-2>. Less
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