# State-of-the-Art Perovskite Solar Cells Benefit from Photon Recycling at Maximum Power Point

## TL;DR

This study demonstrates that photon recycling can significantly enhance the efficiency of state-of-the-art perovskite solar cells at maximum power point, approaching theoretical limits under certain material conditions.

## Contribution

It provides a detailed analysis of photon recycling effects at maximum power point in perovskite solar cells, highlighting conditions for maximum efficiency gains and practical benefits.

## Key findings

- Photon recycling can increase PCE by up to 2.0% at MPP.
- A 77 mV increase in $V_{MPP}$ due to photon recycling.
- Benefits are achievable with non-radiative lifetimes >2 μs and LED EL efficiency >10%.

## Abstract

Photon recycling is required for a solar cell to achieve an open-circuit voltage ($V_{OC}$) and power conversion efficiency (PCE) approaching the Shockley-Queisser theoretical limit. In metal halide perovskite solar cells, the achievable performance gains from photon recycling remain uncertain due to high variability in perovskite material quality and the non-radiative recombination rate ($k_{1}$). In this work, we study state-of-the-art $\textrm{Cs}_{0.05}(\textrm{MA}_{0.17}\textrm{FA}_{0.83})_{0.95}\textrm{Pb}(\textrm{I}_{0.83}\textrm{Br}_{0.17})_{3}$ films and analyze the impact of varying non-radiative recombination rates on photon recycling and device performance. Importantly, we predict the impact of photon recycling at the maximum power point (MPP), demonstrating an absolute PCE increase of up to 2.0% in the radiative limit, primarily due to a 77 mV increase in $V_{MPP}$. Even with finite non-radiative recombination, benefits from photon recycling can be achieved when non-radiative lifetimes and external LED electroluminescence efficiencies measured at open-circuit, $Q_{e}^{LED}(\textrm{V}_{OC})$, exceed 2 $\mu$s and 10%, respectively. This analysis clarifies the opportunity to fully exploit photon recycling to push the real-world performance of perovskite solar cells toward theoretical limits.

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Source: https://tomesphere.com/paper/1901.08637