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The Physics of Ion Migration in Perovskite Solar Cells: Insights into Hysteresis, Device Performance and Characterisation
D. Lan, M.A. Green
Perovskites, other Non-Silicon-Based Photovoltaics and Multi-Junction Devices
Subtopic: Perovskite Based Photovoltaics
Event: 36th European Photovoltaic Solar Energy Conference and Exhibition
Session: 3CO.5.1
ISBN: 3-936338-60-4
0,00 EUR
Document(s): presentation


Mobile ions in perovskite solar cells cause hysteresis in the I–V curves and impact the cell stability and energy conversion efficiency. Although computational studies of this effect have been reported, it is difficult to gain intuitive insights from such high-level treatments. Analytic studies that may lead to better knowledge require the establishment of a solid physics framework. Here, based on the partition of electric potential energy, we propose a generalised mass action law for carriers in perovskites including electrons, holes, mobile ions and vacancies. This allows more intuitive and generalised insights into the hysteresis, cell performance as well as the luminescence both as a characterisation technique and as an application. Aim and approach used The aim of the work is to develop a robust physics framework underpinning the analysis of perovskites as a complex electronic system and to use it to derive better insights into various issues of the area’s interest. For a robust physics framework, we derive a generalised mass action law to account for all charge carriers contributing to the current flow, including electrons, holes, mobile ions and vacancies. The derivation is based on the concept that the gained electric potential energy due to an applied voltage is partitioned among various charge carrier species by their respective charge numbers and displacement from the equilibrium positions. The total energy is conserved with some of the electric potential energy transferred to mechanical energies. These have good implications on how the separation of the electron and hole quasi-Fermi levels in perovskites is modified by mobile ions under various conditions of interest. Then increased insights into various issues are being made possible from both experimental data and the electric field analysis.