成果報告書詳細
管理番号20120000000525
タイトル*平成23年度中間年報 最先端研究開発支援プログラム/低炭素社会に資する有機系太陽電池の開発/超高効率色素増感太陽電池を目指した新規増感色素の探索/有機薄膜太陽電池の劣化機構の解明
公開日2013/1/18
報告書年度2011 - 2011
委託先名独立行政法人産業技術総合研究所
プロジェクト番号P09026
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 1.1. 色素基本情報の構築、色素増感太陽電池の電池特性情報の構築
 色素増感太陽電池において、今後大幅な光電変換効率の向上を達成するためには、可視光だけでなく近赤外光も効率よく光電変換できる高性能増感色素を開発することが必要であり、その場合は増感色素のエネルギー準位を適切な値にチューニングすることが重要となる。色素増感太陽電池では図1に示した電子移動が生じているが、高い変換効率を得るためには、光を吸収し励起状態にある増感色素から酸化チタンの伝導帯への電子注入、及び電解液中のヨウ素レドックスから酸化状態の増感色素への電子注入が効率よく起こることが必須である。光電変換効率の向上のために光吸収領域を長波長化した増感色素は、基底状態と励起状態のエネルギー準位の差が減少するため、電位差も減少する。もし、電位差が小さいと効率の良い電子移動が起こらないため、たとえ光吸収領域を長波長化できたとしても高い変換効率は期待できない。従って、増感色素のエネルギー準位のファインチューニングが求められる。
英文要約Title: R & D on sensitizers toward highly efficient dye-sensitized solar cells Research on degradation
mechanism of organic photovoltaic cells, Development of organic photovoltaics toward a low-carbon
society, Funding Program for World-Leading Innovative R&D on Science and Technology
(FY2010-FY2013) FY2011 Annual Report
Polypyridine ruthenium(II) complexes as sensitizers for dye-sensitized solar cells (DSCs) have been
widely investigated to improve the conversion efficiency of DSCs. The development of sensitizers to
extend the absorption edge is one of the most important issues, as the solar spectrum has a large photon
flux not only in visible region but also in near-IR region.
Polypyridine Ru(II) complexes with bidentate donor ligand(s) were known as sensitizers for DSCs. We
have synthesized and evaluated cyclometalated ruthenium complexes as near-IR sensitizers for
dye-sensitized solar cells. Tuning of the highest occupied molecular orbital (HOMO) energy level by
structural modifications of the ligand improves the conversion efficiency of the cells based on the
complexes up to 10.7%.
Title: Research on degradation mechanism of organic photovoltaic cells, Development of organic
photovoltaics toward a low-carbon society, Funding Program for World-Leading Innovative R&D on
Science and Technology (FY2010-FY2013) FY2010 Annual Report
Organic solar cells (OSCs) have potential advantages in their mechanical flexibility, portability, and
low manufacturing cost. OSCs based on conjugated polymers and soluble fullerenes have been
improved those power conversion efficiencies (PCEs) markedly in the recent decade. Recently, Liang et
al. have developed a thieno[3,4-b]thiophene and benzodithiophene co-polymer (PTB7) as a p-type
semiconducting polymer and achieved very high PCE of over 7%. In contrast to considerable efforts on
improving the PCE of OSCs, researches on the stability of OSCs has been performed only since the last
few years so that the degradation mechanism and key technologies for the long-term stability are still
unclear. In this study, we investigated the stability of high PCE cells with the new polymer PTB7 and
[70]PCBM in comparison to typical P3HT:[60]PCBM cells.
We fabricated PTB7:[70]PCBM cells with high PCEs (average: 7%, maximum: 7.8%) and
P3HT:[60]PCBM cells (average PCE of 2.7%). Under a solar simulated light irradiation (AM 1.5 G,
100 mW/cm2), Voc of the PTB7:[70]PCBM cell was very quickly reduced within 4 hours. We found
that Jsc of the PTB7:[70]PCBM cell was decreased to a half of initial value within 30 hours and was kept
the constant value after 30 hours. On the other hand, the decrease in Jsc of the P3HT:[60]PCBM cell was
small and advanced slowly at this time scale. It is possible that the PTB7:[70]PCBM cell has an another
degradation mechanism such as morphological changes. In addition, we investigate the stabilities of the
cells under several light irradiation conditions. We have found that irradiation of UV light (<450nm)
causes the deterioration of the cell performance in every cells with different photovoltaic materials. It is
possible that UV light creates trapping sites and trapped carriers are accumulated.
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