TY - JOUR
T1 - Modification of nanostructured TiO2 electrodes by electrochemical Al3+ insertion
T2 - Effects on dye-sensitized solar cell performance
AU - Alarcón, Hugo
AU - Hedlund, Maria
AU - Johansson, Erik M.J.
AU - Rensmo, Håkan
AU - Hagfeldt, Anders
AU - Boschloo, Gerrit
PY - 2007/9/6
Y1 - 2007/9/6
N2 - Nanostructured TiO2 films were modified by insertion with aluminum ions using an electrochemical process. After heat treatment these films were found suitable as electrodes in dye-sensitized solar cells. By means of a catechol adsorption test, as well as photoelectron spectroscopy (PES), it was demonstrated that the density of Ti atoms at the metal oxide/electrolyte interface is reduced after Al modification. There is, however, not a complete coverage of aluminum oxide onto the TiO2, but the results rather suggest either the formation of a mixed Al-Ti oxide surface layer or formation of a partial aluminum oxide coating. No new phase could, however, be detected. In solar cells incorporating Al-modified TiO2 electrodes, both electron lifetimes and electron transport times were increased. At high concentrations of inserted aluminum ions, the quantum efficiency for electron injection was significantly decreased. Results are discussed at the hand of different models: A multiple trapping model, which can explain slower kinetics by the creation of additional traps during Al insertion, and a surface layer model, which can explain the reduced recombination rate, as well as the reduced injection efficiency, by the formation of a blocking layer.
AB - Nanostructured TiO2 films were modified by insertion with aluminum ions using an electrochemical process. After heat treatment these films were found suitable as electrodes in dye-sensitized solar cells. By means of a catechol adsorption test, as well as photoelectron spectroscopy (PES), it was demonstrated that the density of Ti atoms at the metal oxide/electrolyte interface is reduced after Al modification. There is, however, not a complete coverage of aluminum oxide onto the TiO2, but the results rather suggest either the formation of a mixed Al-Ti oxide surface layer or formation of a partial aluminum oxide coating. No new phase could, however, be detected. In solar cells incorporating Al-modified TiO2 electrodes, both electron lifetimes and electron transport times were increased. At high concentrations of inserted aluminum ions, the quantum efficiency for electron injection was significantly decreased. Results are discussed at the hand of different models: A multiple trapping model, which can explain slower kinetics by the creation of additional traps during Al insertion, and a surface layer model, which can explain the reduced recombination rate, as well as the reduced injection efficiency, by the formation of a blocking layer.
UR - http://www.scopus.com/inward/record.url?scp=34648846226&partnerID=8YFLogxK
UR - http://dx.doi.org/10.1021/jp072641n
U2 - 10.1021/jp072641n
DO - 10.1021/jp072641n
M3 - Artículo (Contribución a Revista)
AN - SCOPUS:34648846226
SN - 1932-7447
VL - 111
SP - 13267
EP - 13274
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 35
ER -