| 研究実績の概要 |
I successfully replaced conventional materials, which limit the potentials of thin-film solar cells, namely, low-cost fabrication, and power conversion efficiency, by using earth-abundant carbon allotropes, such as fullerene and carbon nanotubes. I discovered that fullerene can replace metal oxides, resulting in perovskite solar cells with no hysteresis and much improved stability. In addition, carbon nanotubes replaced the top metal electrodes, functioning as a better moisture barrier and preventing ion migration-induced degradation. Thereby, we realised the carbon-sandwiched perovskite solar cells, which was publlished in J. Mater. Chem. A, 6, 1382. Moreovere, I used endohedral fullerene for the first time in device to replace conventional hygroscopic dopant, lithium bis(trifluoromethanesulfonyl)imide. I discovered the new lithium ion-containing endohedral fullerene not only suppress the hygroscopicity of the dopant, but also lead to a new reaction mechanism with 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobi-fluorene. This results in an anti-oxidation activity within the perovskite solar cells, and ultimately improving the device stability greatly (Angew. Chem. Int. Ed. 57, 1). It was unfortunate that we did not have enough time to finish the next step, which were the application of new polymeric hole-transporting materials and the lithium ion-containing endohedral fullerene to carbon nanotube top electrode. This work will be continued using the JSPS WAKATE grant which I secured this year.
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