REE6: Current generation in photovoltaic cells
| Researcher: | Savina Joseph |
| Team Leader(s): | Prof. John Ockendon, Dr Chris Breward, Dr Andreas Münch & Prof. Colin Please |
| Collaborators: | Dr Giles Richardson, Southampton University |
| Dr Rick Hamilton, Solar Press |
Background
A solid-state dye-sensitised solar cell (ssDSSC) is a new,
cheaper type of solar cell that could compete economically with the
conventional silicon solar cells. Enhancing or suppressing features of the cell
could increase its efficiency and allow its entry to the market. Our aim is to
describe the operation of ssDSSCs mathematically to investigate the effects of
features of the cell. We will compare our model to experimental data.
Techniques and Challenges
An ssDSSC consists of five layers: the anode, the electron acceptor (EA) layer, the dye monolayer, the electron donor (ED) and the cathode – each layer with its own parameters. The challenge is to understand the chemical interactions and the interdependencies between the parameters of the problem, and also to model the geometry of the mesoporous EA layer. We have started with the case of a flat EA/ED interface, neglecting the porosity of the EA. Our model couples ordinary differential equations (ODEs) describing the electrostatic potential throughout the cell, and the electron/hole densities and fluxes in disjoint regions with current generation conditions at the dye interface. These conditions are determined by solving a dynamic system for the dye.
Results
So far, our model for the relation between the voltage and the current generated by the cell qualitatively agrees with the experimental data for a flat bilayer ssDSSC. Further, numerical simulation has shown that key parameters have an effect on the overall efficiency of the cell.
The Future
By fitting the parameter values in our model using the experimental data, we should be able to investigate the parameters’ interdependencies and improve our model. We would also like to solve the model on a more complicated geometry of the mesoporous layer.
References
[11/61] Richardson G., Please C.P., Kirkpatrick J.: Asymptotic solution of a model for bilayer organic diodes and solar cells, SIAP, Submitted.
Bach U., Graetzel M., et al: Solid-state dye-sensitised mesoporous TiO2 solar cells with photo-to-electron conversion efficiencies, Nature, 395:583-585, 1998
Penny M.: Mathematical Modelling of dye-sensitised solar cells, PhD thesis, Queensland University of Technology, 2006