Weisspfennig, CT and Lee, MM and Teuscher, J and Docampo, P and Stranks, SD and Joyce, HJ and Bergmann, H and Bruder, I and Kondratuk, DV and Johnston, MB and Snaith, HJ and Herz, LM (2013) Optimizing the energy offset between dye and hole-transporting material in solid-state dye-sensitized solar cells. Journal of Physical Chemistry C, 117. pp. 19850-19858. ISSN 1932-7447Full text not available from this repository.
The power-conversion efficiency of solid-state dye-sensitized solar cells can be optimized by reducing the energy offset between the highest occupied molecular orbital (HOMO) levels of dye and hole-transporting material (HTM) to minimize the loss-in-potential. Here, we report a study of three novel HTMs with HOMO levels slightly above and below the one of the commonly used HTM 2,2′,7,7′- tetrakis(N,N-di-p-methoxyphenylamino)-9,9′- spirobifluorene (spiro-OMeTAD) to systematically explore this possibility. Using transient absorption spectroscopy and employing the ruthenium based dye Z907 as sensitizer, it is shown that, despite one new HTM showing a 100% hole-transfer yield, all devices based on the new HTMs performed worse than those incorporating spiro-OMeTAD. We further demonstrate that the design of the HTM has an additional impact on the electronic density of states present at the TiO2 electrode surface and hence influences not only hole- but also electron-transfer from the sensitizer. These results provide insight into the complex influence of the HTM on charge transfer and provide guidance for the molecular design of new materials. © 2013 American Chemical Society.
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|Date Deposited:||04 Feb 2015 22:38|
|Last Modified:||16 Feb 2015 01:18|