Towards the use of CMOS technologies and concepts for the production of transparent
conducting oxide thin films for use in next-generation solar harvesting devices
Martyn E Pemble
1,2*
, Jennifer Halpin
2
, Igor Kazadojev
2
, Jan Kegel
2
, Melissa McCarthy
2
, Mircea
Modreanu
2
, Shane O’Brien
2
, Ian M Povey
2
, Louise P Ryan
2
and Adrian Walsh
2
1
Department of Chemistry, University College Cork, Cork, Republic of Ireland
2
Tyndall National Institute, University College Cork, Lee Maltings, Cork, Republic of Ireland
*
Author for correspondence
TCM’s and in particular transparent conducting oxides (TCOs) are optically transparent and
electrically conductive materials that are now well-established for application in areas such as
photovoltaic (PV) energy harvesting, touch screen displays, liquid crystal displays, electrochromic
switching and organic light emitting diodes (OLEDs). In addition to the inorganic oxides such as
indium tin oxide, F-doped tin oxide, doped zinc oxide etc., other materials have emerged as having
potential use in some of these application areas, e.g. thin metal films, metal nanowire grids,
conducting polymers, graphene and carbon nanotubes. In the final assessment it is very likely that
materials will be selected based upon technical performance in relation to the specific application
(how conducting, how transparent and over what spectral region?) and cost of production.
This patter point is of course paramount. Here the various application industries noted above can learn
considerably from the electronics industry, which as a result of the application of Moore’s Law and
other drivers, has become the epitome of high-volume manufacturing streamlining and cost reduction.
This learning process is now well underway. In particular in our laboratories based on our extensive
experience of CMOS processing we are now making thinner films of materials such as TCOs, with a
view to not only reducing the cost of materials but also improving the performance of the device and
ultimately to making the production of devices more economically and politically attractive. This
latter point is an important one particularly from the renewable energy consideration. We already have
the technology to harvest as much energy from the sun as we would ever need, but we need to make
this technology so easy to adopt and so cheap to make and maintain that it essentially becomes a ‘no-
brainer’ such that the fossil fuel lobby has no realistic case to make against this concept.
This presentation will discuss the issues associated with using CMOS-based technologies and
concepts to optimise increasingly thin TCO materials for a variety of applications, necessarily
focussing on the interfacial issues which arise naturally, as materials get thinner. Examples will be
given on the use of TCOs as both protection layers and absorber layers for photocatalytic water
splitting and as ultrathin transparent conducting electrodes (electron and hole transport layers) for
conventional and emerging PV devices.
This work is supported by Science Foundation Ireland (SFI) grant number 13/US/I2543, RENEW-
Research into Emerging Nanostructured Electrodes for the Splitting of Water and SFI Principal
Investigator grant number 11/PI/1117, together with EU FP7 grant PLIANT and EU H2020 grant
CHEOPS.
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