HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 287
C145 - Electrodeposited ZnO Nanorods for Dye-Solar Cells
Tânia Frade b , Killian Lobato a , Anabela Gomes b
a, SESUL - Centre for Sustainable Energy Systems of the University of Lisbon, Faculdade de Ciências da Universidade de Lisboa,
Edifício C8, Lisboa, 1749-016, Portugal
b, CCMM - Centro de Ciências Moleculares e Materiais, Faculdade de Ciências da Universidade de Lisboa, Edifício C8, Lisboa, 1749-
016, Portugal
The dye-solar cell (DSC) offers a fascinating paradigm with regards the generation of
electricity directly from sunlight. There are a wide variety of architectures possible and one of
the many components in a DSC that can be altered is the supporting structure onto which the
dye is adsorbed. However there is fundamental prerequisite, that it have a high internal
surface area. The use of suspensions of nanoparticles which are deposited onto TCOs and then
sintered, tend to be more facile manner or preparing such structures. This is possible with a
variety of semiconductors e.g. TiO2, ZnO, WO3, etc. However, the only simple manner in which
an intimate contact can be obtained between the adsorbed dye-monolayer electron donor
species to regenerate the oxidized dye, is via the use of liquid electrolytes. However, it is
difficult to envisage a PV device for utility scale deployment that contains an encapsulated
liquid. For this reason, the structure of the photoanode must be one that is amenable to the
substitution of the liquid electrolyte for an organic or inorganic hole-transport-medium,
providing the same intimate contact that is possible with an electrolyte. The simplest solution
one can invisage is the use of highly orientated vertical nanostrucutures. This type of structure
is easily attainable via the electrodeposition of ZnO and there are several reports describing
the electrodeposition with conditions explored resulting in a variety of geometries e.g. rods,
needle, tubes and porous layers[1–3]. This has the added bonus in that these structures can be
obtained at relatively low temperatures, allowing the use of organic-TCO coated substrates
that are lightweight and flexible.
Here we will present a simple approach to produce high-density vertically aligned ZnO
nanorod arrays on F-doped SnO2 (FTO) coated glass substrates, prepared at 70ºC from a
neutral zinc nitrate solution[4]. Electrodeposition parameters, namely deposition time and
bath composition were varied and the effects on film crystallinity, morphology and DSC device
performance have been characterized.
Figure 1 SEM image of ZnO nanorod arrays on FTO substrates prepared by electrodeposition method. Inset:
Diffractogram of ZnO nanorod arrays.
Film composition and morphology was characterized via XRD and FEG-SEM whilst DSC
device charge transport and recombination properties were characterized via AM1.5 solar
© SEFIN 2012