Rediscovering a Key Interface in Dye-Sensitized Solar Cells: Guanidinium and Iodine Competition for Binding Sites at the Dye/Electrolyte Surface

Autor:	Brian C. O’Regan, Xavier A. Jeanbourquin, Robin Humphry-Baker, Xiaoe Li, Peter Lund, Piers R. F. Barnes, Muhammad Asghar, ChunHung Law
Rok vydání:	2014
Předmět:	Photocurrent Passivation Inorganic chemistry chemistry.chemical_element General Chemistry Electrolyte Iodine Biochemistry Catalysis Guanidinium thiocyanate chemistry.chemical_compound Dye-sensitized solar cell Colloid and Surface Chemistry chemistry Molecule Recombination
Zdroj:	Journal of the American Chemical Society. 136:7286-7294
ISSN:	1520-5126 0002-7863
DOI:	10.1021/ja411560s
Popis:	We propose a new mechanism by which the common electrolyte additive guanidinium thiocyanate (GdmSCN) improves efficiency in dye-sensitized solar cells (DSSCs). We demonstrate that binding of Gdm(+) to TiO2 is weak and does not passivate recombination sites on the TiO2 surface as has been previously claimed. Instead, we show that Gdm(+) binds strongly to the N719 and D131 dyes and probably to many similar compounds. The binding of Gdm(+) competes with iodine binding to the same molecule, reducing the surface concentration of dye-I-2 complexes. This in turn reduces the electron/iodine recombination rate constant, which increases the collection efficiency and thus the photocurrent. We further observe that GdmNO(3) can increase efficiency more than the current Gdm(+) source, GdmSCN, at least in some DSSCs. Overall, the results point to an improved paradigm for DSSC operation and development. The TiO2/electrolyte surface has long been held to be the key interface in DSSCs. We now assert that the dye layer/electrolyte interaction is at least, and probably more, important.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::65fd90977fd8312498a82e0c28692802 https://doi.org/10.1021/ja411560s Zobrazit plný text záznamu