What can J–V hysteresis tell us about defect mediated phenomena in perovskite based solar cells?

Matthew Cowley^a^,^b, William Clarke^c, Matthew Wolf^d, Giles Richardson^c, Alison Walker^e, Petra Cameron^b

^aCentre for Sustainable and Circular Technologies, University of Bath

^bDepartment of Chemistry, University of Bath, Claverton Down, University of Bath, Bath,UK, BA2 7AY, United Kingdom

^cDepartment of Mathematical Sciences, University of Southampton, University of Southampton, Southampton, SO17 1BJ, United Kingdom

^dInstitute of Physical Chemistry, RWTH Aachen University

^eDepartment of Physics, University of Bath, Claverton Down, Bath, United Kingdom

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)

València, Spain, 2022 May 19th - 25th

Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson

Oral, Matthew Cowley, presentation 139
DOI: https://doi.org/10.29363/nanoge.hopv.2022.139
Publication date: 20th April 2022

J–V scans of lead-halide perovskite solar cells can show higher fill factors and open-circuit voltages during the reverse sweep depending on measurement conditions,[1] a phenomenon known as J–V hysteresis. A consensus has emerged that this behaviour is due to the halide ion vacancy distribution adjusting to the preconditioning voltage and screening the built-in potential. During the J–V protocol the ion distribution lags behind the applied voltage and the bulk electric field changes in size – modulating the extracted current.[2] The inverted scenario of the reverse to forward bias sweep showing ostensibly improved J–V characteristics, has also been measured.[3] The presence of hysteresis is typically seen as a negative, but due to its dependence on the measurement protocol hysteresis can be used to help characterise the cell.

Here we simulate both n-i-p and p-i-n cells that show normal and inverted hysteresis within a single parameter set using drift-diffusion modelling. The key parameters responsible for these effects are demonstrated. The voltage programme for the J–V experiment is shown to be crucial in determining the behaviour seen, and measurement protocols where J–V curves cannot be used to accurately characterise the cell are identified. The J–V scan is described by differences in the fill-factor, open-circuit voltage, and short-circuit current and the underlying mechanisms are explored. The effect of recombination and generation location is investigated – outlining how voltage protocol and illumination wavelength can help determine defect site location.

References:

[1] Pockett, A. et al. Microseconds, milliseconds and seconds: Deconvoluting the dynamic behaviour of planar perovskite solar cells. Phys. Chem. Chem. Phys. 19, 5959–5970 (2017).

[2] Courtier, N. E., Cave, J. M., Foster, J. M., Walker, A. B. & Richardson, G. How transport layer properties affect perovskite solar cell performance: insights from a coupled charge transport/ion migration model. Energy Environ. Sci. 12, 396–409 (2019).

[3] Shen, H. et al. Inverted Hysteresis in CH3NH3PbI3 Solar Cells: Role of Stoichiometry and Band Alignment. J. Phys. Chem. Lett. 8, 2672–2680 (2017).

Acknowledgements:

MVC is supported by the EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies EP/L016354/1

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