Characterization of pore-filling of spiro-MeOTAD in solid-state dye-sensitized solar cells and its consequence in device performance

I-Kang Ding, Nicolas Tétreault, Brian E. Hardin, Eva H. Smith, Michael Grätzel, Michael D. McGehee

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In this paper, the pore filling of spiro-MeOTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)9, 9'-spirobifluorene) in mesoporous TiO2 films is quantified for the first time using XPS depth profiling and UVVis absorption spectroscopy. We show that spiro-OMeTAD can penetrate the entire depth of the film, and its concentration is constant throughout the film. We determine that in a 2.5-•m-thick film, the volume of the pores is 60-65% filled. The pores become less filled when thicker films are used. Such filling fraction is much higher than the solution concentration because the excess solution on top of the film can act as a reservoir during the spin coating process. Lastly, we demonstrate that by using a lower spin coating speed and higher spiro-OMeTAD solution concentration, we can increase the filling fraction and consequently the efficiency of the device
Original languageEnglish (US)
Title of host publicationOrganic Photovoltaics X
PublisherSPIE-Intl Soc Optical Eng
ISBN (Print)9780819477064
StatePublished - Aug 27 2009
Externally publishedYes

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