  Graphene has been used recently as a replacement for indium tin oxide (ITO)
for the transparent electrode of an organic photovoltaic device. Due to its
limited supply, ITO is considered as a limiting factor for the
commercialization of organic solar cells. We explored the use of large-area
graphene grown on copper by chemical vapor deposition (CVD) and then
transferred to a glass substrate as an alternative transparent electrode. The
transferred film was shown by scanning Raman spectroscopy measurements to
consist of >90% single layer graphene. Optical spectroscopy measurements showed
that the layer-transferred graphene has an optical absorbance of 1.23% at a
wavelength of 532 nm. We fabricated organic hybrid solar cells utilizing this
material as an electrode and compared their performance with ITO devices
fabricated using the same procedure. We demonstrated power conversion
efficiency up to 3.98%, higher than that of the ITO device (3.86%), showing
that layer-transferred graphene promises to be a high quality, low-cost,
flexible material for transparent electrodes in solar cell technology.

Materials Science;Mesoscale and Nanoscale Physics