I mentioned previously the title of my dissertation this year, thought I would take the time to write a quick summary of what it is all about here.
Organic Photovoltaic Solar Cells (abbreviated to OPVs) are solar cells where the active layer (the layer that turns light energy into electricity) is made of an organic material, rather than Silicon. OPVs currently suffer from having much lower efficiencies than traditional silicon solar cells, so my project was set up to attempt to optimise OPV efficiency.
All solar cells have a transparent electrode layer which must be transparent to light from the sun but also highly conductive – two characteristics which are normally mutually exclusive in common materials. However, there is a set of materials known as Transparent Conducting Oxides (TCOs) exhibit both of the required properties. A commonly used TCO in OPVs is Indium Tin Oxide (ITO) which is the main focus of my project.
This research simulates an OPV solar cell using a Thin Film Multiple Reflection model, and by varying all of the parameters of the ITO layer we can calculate and plot the efficiency of the cell. The simulation varies all of the main parameters of the ITO layer giving millions of possible combinations (which is made possible thanks to HPC Wales donating some Super Computer time to us) in order to find the optimum parameters for the investigated layer.
It is interesting stuff and it’s an area of electronics that has been investigated previously by others, but as far as I am aware the overall optimum model has never been calculated before.
I am currently midway through building the final simulation, but already it is possible to see a large range of device efficiencies emerging and this alone may lead to small improvements in OPV solar cell efficiency in the future.