Some people might be surprised
and sceptical when reading the title of this post, since they might presume
that a material absorbing light cannot be transparent. However this could be
possible since the sunlight spectrum is not only formed by UV-Visible light but
it also has a large percentage (~50 %) of IR light. If we can make a cell only absorbing
UV and/or IR, we can have a transparent device, which is the novel polymer
solar cell presented by Yang Yang and collaborators from the University of
California, Los Angeles (UCLA).
These cells open the possibility
of energy harvesting in a new wide range of applications such as windows and portable
electronics, where you could be able to charge your mobile from the energy collected
by the screen. This novel device relies on two achievements. First, a polymeric
material sensitive to near-IR light but highly transparent to visible light. Secondly, high performance Ag nanowire-based composite works as the
transparent conductive material in the cathode, role usually adopted by different
metals that are opaque. The device reaches almost 70% transparency at 550 nm
with an overall 4% efficiency.
