| Budget Amount *help |
¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2014: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2013: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2012: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Outline of Final Research Achievements |
The blend films of conducting polymers and fullerenes have been widely studied for photovoltaic applications. In this study, conduction and recombination mechanisms of charge carriers in these blend films are clarified by using electron spin resonance (ESR) spectroscopy, together with the conductivity measurements. The blends using semicrystalline polymers exhibit quadrimolecular recombination kinetics of photogenerated carriers, where two positive polarons on the polymer chain and two fullerene radical anions annihilate simultaneously, up to room temperature. This process presumably originates from the formation of doubly-charged bipolarons on the ordered polymer chain. In addition, carrier mobilities are directly determined from the FET characteristics. The hole mobility depends on the mixing ratio of the fullerene through the change of polymer orientation. It is clarified that the photon-to-current efficiency shows maximum where the electron and hole mobilities match each other.
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