Project title: Modelling of interfacial hole hopping in solid state dye sensitized solar cells
Supervisors: Prof Jenny Nelson, Dr Piers Barnes and Dr James Kirkpatrick
In dye-sensitised solar cells, photocurrent is generated by light absorption in dye molecules attached to the surface of a porous metal oxide electrode, followed by electron transfer from the dye into the metal oxide, and hole transfer from the dye to a hole transport medium (HTM). However, the HTM may not easily infiltrate into the pores of the oxide electrode, leaving areas where the HTM is unable to discharge the dye and therefore no photocurrent is produced. A solution is to use dyes that are able to transfer positive charge between one another via “hole hopping” whereby charges percolate along the oxide surface through dye molecules . In this project we aim to model the hole hopping process via a multiscale approach. We will use a combination of quantum chemical techniques and Monte Carlo methods to simulate the transfer and transport of charge along a dye sensitized surface, as a function of the density of dyes; the dye chemical structure, separation and relative orientation; and the geometry of the surface. Model results will be compared with recent experimental results that show that for some types of dye, hole hopping improves photocurrent generation for poorly infiltrated HTM materials .
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