a) Device simulations of hysteresis versus ion density and JV-scan speed. b) Efficiency vs. scan speed for different ion densities. c) Predicted efficiency as a function of different recombination properties at the interfaces. d),e) Band diagrams of perovskite solar cells and f) charge carrier density profiles under open-circuit conditions.
(III) Device Simulations
Considering the complexity of recombination processes in solar cells and in multilayered perovskite cells in particular, numerical simulations are required to improve the understanding of the experimental results. A quantitative description of perovskite solar cell operation remains a challenging task and more research is required to understand key aspects such as the bandstructure and energy alignment and the interplay between charge extraction and recombination processes. In perovskites, this is further complicated by the vast amount of mobile ions in the active layer that slowly sweep the active layer, depending on the applied voltage and the operating point of the cell.
The Perovskite Group has developed numerical models to describe solar cells by considering the input from various experimental measurements in steady-state and in transient mode such as the rate constants of recombination and mobilities (find out more). To this end, we employ open-source codes such as SCAPS as well as self-written codes.
A key objective of the group is the development of numerical models that describe steady state solar cell operation, electrical transient measurements, tandem solar cells and the impact of mobile ions.
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- Stolterfoht, M. et al. The impact of energy alignment and interfacial recombination on the internal and external open-circuit voltage of perovskite solar cells. Energy Environ. Sci. 12, 2778–2788 (2019).
- Caprioglio, P. et al. On the Relation between the Open‐Circuit Voltage and Quasi‐Fermi Level Splitting in Efficient Perovskite Solar Cells. Adv. Energy Mater. 9, 1901631 (2019).