A d
oubly c
oaxial ph
ot
oan
ode architecture based
on templated SiO
2 aer
ogels was fabricated
on transparent c
onducting
oxides f
or use in dye-sensitized s
olar cells (DSSCs). These templates were c
oated with ZnO
via at
omic layer dep
ositi
on (ALD) t
o yield an electr
onically interc
onnected, l
ow-density, high-surface-area, semic
onduct
or framew
ork. Additi
on
of a thin c
onf
ormal layer
of a sec
ond metal
oxide (alumina, zirc
onia,
or titania)
via ALD was f
ound t
o suppress the diss
oluti
on
of ZnO that
otherwise
occurs when it is s
oaked in alc
oh
ol s
oluti
ons c
ontaining acidic dyes used f
or sensitizati
on
or in acet
onitrile s
oluti
ons c
ontaining a pyridine derivative and the i
odide/tri-i
odide (I
鈥?/sup>/I鈥?/sup>3) redox shuttle. Electron transport in SiO2鈥揨nO鈥揟iO2 photoelectrodes was found to be nearly 2 orders of magnitude faster than in SiO2鈥揟iO2 structures, implying that the interior ZnO sheath serves as the primary electron conduit. In contrast, rates of electron interception by the oxidized form of the redox shuttle were observed to decrease when a TiO2 shell was added to SiO2鈥揨nO, with the decreases becoming more significant as the thickness of the titania shell increases. These effects lead to improvements in efficiency for DSSCs that utilize I鈥?/sup>/I鈥?/sup>3, but much larger improvements for DSSCs utilizing ferrocene/ferrocenium, a notoriously fast redox shuttle. For the former, overall energy conversion efficiencies maximize at 4.0%. From a variety of experiments, the primary factor limiting aerogel-based DSSC performance is light loss due to scattering. Nevertheless, variants of the doubly coaxial structure may prove useful in devising DSSCs that can achieve excellent energy conversion efficiencies even with fast redox shuttles.
Keywords:
ors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=dye%5C-sensitized+solar+cell&qsSearchArea=searchText">dye-sensitized solar cell; ors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=atomic+layer+deposition&qsSearchArea=searchText">atomic layer deposition; ors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=zinc+oxide&qsSearchArea=searchText">zinc oxide; ors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=aerogel&qsSearchArea=searchText">aerogel; ors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=ferrocene+redox+shuttle&qsSearchArea=searchText">ferrocene redox shuttle