Spatial Mapping of Transient Electroluminescence in Perovskite Solar Cells
Evelyne Knapp a, Ennio Comi a, Mattia Battaglia a, Beat Ruhstaller a b, Miguel Angel Torre Cachafeiro a, Sandra Jenatsch b, Balthasar Blülle b
a Zurich Univ. of Appl. Sciences (ZHAW), Inst. of Computational Physics
b Fluxim AG, 8400 Winterthur, Switzerland
Proceedings of Device Physics Characterization and Interpretation in Perovskite and Organic Materials (DEPERO)
València, Spain, 2023 October 3rd - 5th
Organizers: Sandheep Ravishankar, Juan Bisquert and Evelyne Knapp
Invited Speaker, Evelyne Knapp, presentation 031
Publication date: 14th September 2023

In our study of carbon-based hole-transporter-free PSCs with mesoporous layers, we observed pronounced local variations in Electroluminescence (EL) of turn-on dynamics, consistent with prior research but with notable local enhancements in EL intensity. To elucidate these variations, we employed a 1D drift-diffusion simulation (Setfos 5.3) to model the device stack, fitting material parameters and using a recombination-coupled emission model to simulate transient EL signals.

Our simulations revealed that locally increased ion densities could account for the stronger EL signal at specific positions. The temporal behavior of this phenomenon is strongly influenced by the mobility of iodine vacancies. The results of the 1D drift-diffusion model were integrated into the 2D+1D FEM software tool Laoss to account for sheet resistances on the top and bottom electrodes [1], thereby explaining potential drops detectable in EL images. The FEM tool also facilitated qualitative comparisons with EL images by displaying simulated transient luminescence results in 2D.

In summary, our study of mesoporous perovskite solar cells' transient EL images revealed local ion density variations, reproduced through a combination of 1D drift-diffusion and 2D+1D FEM simulations. These findings underscore the impact of mobile ionic charge carriers on the long-term performance of PSCs, with spots exhibiting increased ionic concentrations potentially serving as vulnerable points susceptible to degradation.

We acknowledge the financial support of Innosuisse (58054.1 IP-EE).

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