HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 131
C25 - Optically-thin gold electrodes on flexible polyester substrates for organic
photovoltaics
Ross Hatton, Helena Stec
University of Warwick, Library Road, Coventry, CV4 7AL, GB
We report an innovative scalable protocol for the preparation of nano-thickness (5.6 – 8.4
nm), ultra-smooth Au electrodes on the technologically important transparent flexible
substrates polyethylene naphthalate (PEN) and polyethylene terephthalate (PET). The key step
in the preparation of these films is derivatization of the plastic surface with a molecular
nanolayer prior to metal deposition. Crucially the nanolayer is deposit from the vapour phase
under low vacuum, avoiding complexity resulting from the use of solvents and rendering it
scalable. The resulting films are highly electrically conductive, highly transparent and
remarkably robust towards ultra-sonication in common solvents.
Figure 1
Furthermore, brief thermal annealing dramatically alters the film microstructure such that
the electrode surface reverts almost entirely to the (111) crystal face. We show that the
performance of 1.0 cm 2 organic photovoltaic devices supported on these electrodes is
comparable to that achieved on commercially available indium-tin oxide coated PET
substrates, whilst only the former are resistant to repeated bending through a small radius of
curvature. Vacuum deposition of the window electrode opens the door to the fabrication of
entire molecular photovoltaics under the same vacuum, greatly increasing the economic
viability of this class of organic photovoltaic.
© SEFIN 2012