Modelling Ion Motion and Hysteresis in Perovskites
Organolead halide perovskite solar cells have shown dramatic increases in efficiency to around 20% since their inception in 2012. Nevertheless there is still, at best, only a partial understanding of the charge transport processes occurring in these cells. One particularly vexed issue is that of slow relaxation of the current (occurring on a 100s timescale) after a change in the illumination or applied voltage. Various mechanisms have been proposed to explain this relaxation process including ion motion within the perovskite structure for which there is now significant evidence. The goal of this project is to formulate, and solve, charge transport models for the operation of perovskite cells that explicitly include ion motion. The results of these models will be compared to experimental results generated by our collaborators in Chemistry at Bath (and elsewhere) and used to inform the modelling. The implications of ion motion on cell degradation (a major issue in perovskites) and reduced efficiency will be considered. The project will combine modelling techniques together with numerical (i.e. computational) and analytic methods.