Rigorous optoelectronic modeling of luminescent coupling phenomena in perovskite solar cells

Simon J. Zeder¹, Tabea Krucker^2,3, Davide Moia¹, Beat Ruhstalle^r1,3, Urs Aeberhard¹

¹Fluxim AG, Switzerland

²EPFL PV-Lab, Switzerland

³ZHAW Institute of Computational Physics, Switzerland

E-mail:simon.zeder@fluxim.com

Abstract

Multi-junction  solar  cells  that  combine  absorbers  of  varying  band  gaps  to  enhance  the utilization of the broadband solar spectrum by reducing transmission and thermalization loss represent the highest efficient photovoltaic devices and a vastly successful implementation of a concept aiming at power conversion efficiencies beyond the single junction detailed balance limit.  However, the ultra-high efficiencies come at the cost of increased complexity, not only in the device layout, where stacks with a large number of different layers dominate, but also in operation.

Especially in the domain of monolithically integrated two-terminal devices, where the sub-cells are connected in series, the stack layout needs to be designed carefully in order to balance the currents at the relevant point of operation, which is usually the maximum power point. This then regards not only the photocurrent, but also the currents due to recombination of electrically or optically injected charge carriers.

Recombination is affected by the details of charge transport in the actual device configuration, such as mobilities of charge carriers and the presence of extraction barriers, which can also be affected by the device operation, as internal fields vary under bias voltage or due to the impact of mobile ions. Additionally, in the material systems that are often used for top cells, such as III-V semiconductors or metal-halide perovskites, the high radiative efficiencies and steep absorption edges promote contributions from re-absorption of internally emitted photons in the form of additional generation due to photon recycling and luminescent coupling. Since this secondary generation stems from internal photon emission, it is also directly coupled to the internal recombination characteristics. The relevance of these phenomena comes not only from their impact on direct device performance but also from their nontrivial effects on experiments for device characterization such as EQE measurements.

For such cases, detailed numerical simulation of solar cell operation can support the design, analysis and optimization of the photovoltaic device architectures.

In this presentation, I discuss our recent efforts [1-5] towards a versatile numerical simulation tool suited for supporting research and development in the field of tandem photovoltaics. I will introduce first the general implications of luminescent coupling effects in solar cells before giving a high-level overview of the modelling approaches thereof. This is followed by specific results for real-world systems in terms of PV performance and device characterization, such as monochromatic EQE measurements in perovskite-silicon tandems for model validation.

References:

[1]S.J. Zeder, B. Blülle, B. Ruhstaller, U. Aeberhard, “Optimizing perovskite LEDs and tandem PV cells: The role of photon- recycling and luminescent coupling in presence of strong light scattering”, APL Energy 3, 026110 (2025).

[2]  S. J. Zeder, B. Blülle, B. Ruhstaller, U. Aeberhard, “Optical multiscale model for quantification of photon recycling including incoherent light scattering,” Opt. Express 32, 34154 (2024).

[3]  S. J. Zeder et al, “Impact of Luminescent Coupling on Perovskite-Silicon Tandem EQE Quantified by Comprehensive Opto-Electronic Simulation”, Solar RRL (under review)

[4]  U Aeberhard et al, “Multi-Scale Simulation of Reverse-Bias Breakdown in All-Perovskite Tandem Photovoltaic Modules under Partial Shading Conditions”, Solar RRL 8, 2400492 (2024).

[5]  U. Aeberhard,  S. J. Zeder, B. Ruhstaller, “Effects of Photon Recycling and Luminescent Coupling in All-Perovskite Tandem Solar Cells Assessed by Full Opto-Electronic Simulation”, Solar RRL 8, 2400264 (2024).