Oxygen-Induced Doping of Spiro-MeOTAD in Solid-State Dye-Sensitized Solar Cells and Its Impact on Device Performance
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- 作者：Ute B. Cappel ; Torben Daeneke ; Udo Bach
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：September 12, 2012
- 年：2012
- 卷：12
- 期：9
- 页码：4925-4931
- 全文大小：338K
- 年卷期：v.12,no.9(September 12, 2012)
- ISSN：1530-6992
文摘
Solid state dye-sensitized solar cells (sDSCs) employing the hole conductor 2,2鈥?,7鈥?tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9鈥?spirobifluorene (spiro-MeOTAD) require the presence of oxygen during fabrication and storage. In this paper, we determine the concentrations of oxidized spiro-MeOTAD within devices under different operating and storage conditions by UV鈥搗is spectroscopy. Relative concentrations of spiro-MeOTAD+ were found to be greater than 10% after illumination for standard sDSCs, where no chemical dopant had been used in the solar cell fabrication but oxygen and lithium ions were present. We suggest that oxidized spiro-MeOTAD is created as a byproduct of oxygen reduction at the TiO2 surface during cell illumination. Furthermore, we studied the effect of light soaking under different conditions and associated changes in spiro-MeOTAD+ concentration on the solar cell measurements. Our findings give insights to photochemical reactions occurring within sDSCs and provide guidelines for which doping levels should be used in device fabrication in absence of oxygen.