Photon recycling is required for a solar cell to achieve an open-circuit voltage and power conversion efficiency (PCE) approaching the Shockley-Queisser theoretical limit. The achievable performance gains from photon recycling in metal halide perovskite solar cells remain uncertain due to high variability in material quality and the non-radiative recombination rate. In this work, we quantify the enhancement due to photon recycling for state-of-the-art perovskite Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3 (triple-cation) films and corresponding solar cells. We show that, at the maximum power point (MPP), the absolute PCE can increase up to 2.0% in the radiative limit, primarily due to a 77 mV increase in . For this photoactive layer, 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, , exceed 2 µs and 10%, respectively. This analysis quantifies the significance of photon recycling in boosting the realworld performance of perovskite solar cells toward theoretical limits.

A comprehensive framework for modeling energy carrier transport upon optical excitation in both excitonic and free carrier semiconductors is developed and applied. Using metal halide perovskite thin films as a model system, we demonstrate that processes such as nonlinear recombination and photon recycling can have a significant impact on the measured energy carrier profiles, especially for excitonic materials with short radiative lifetimes. Additionally, we find that film microstructure can lead to unique transport profiles that strongly depend on the material boundary behavior and the differences between the domain feature size and the energy carrier diffusion length. Our analysis provides a rigorous model of energy transport in semiconducting materials and a detailed assessment of the fundamental parameters needed for the design and optimization of electronic and optoelectronic devices.

Despite rapid advancements in power conversion efficiency in the last decade, perovskite solar cells still perform below their thermodynamic efficiency limits. Non-radiative recombination, in particular, has limited the external radiative efficiency and open circuit voltage in the highest performing devices. We review the historical progress in enhancing perovskite external radiative efficiency and determine key strategies for reaching high optoelectronic quality. Specifically, we focus on non-radiative recombination within the perovskite layer and highlight novel approaches to reduce energy losses at interfaces and through parasitic absorption. By strategically targeting defects, it is likely that the next set of record-performing devices with ultra-low voltage losses will be achieved.

Hybrid perovskites have emerged as a promising material candidate for exciton-polariton (polariton) optoelectronics. Thermodynamically, low-threshold Bose-Einstein condensation requires efficient scattering to the polariton energy dispersion minimum, and many applications demand precise control of polariton interactions. Thus far, the primary mechanisms by which polaritons relax in perovskites remains unclear. In this work, we perform temperature-dependent measurements of polaritons in low-dimensional perovskite wedged microcavities achieving a Rabi splitting of $${{{\hslash }}\Omega }_{{Rabi}}$$ ℏ Ω R a b i  = 260 ± 5 meV. We change the Hopfield coefficients by moving the optical excitation along the cavity wedge and thus tune the strength of the primary polariton relaxation mechanisms in this material. We observe the polariton bottleneck regime and show that it can be overcome by harnessing the interplay between the different excitonic species whose corresponding dynamics are modified by strong coupling. This work provides an understanding of polariton relaxation in perovskites benefiting from efficient, material-specific relaxation pathways and intracavity pumping schemes from thermally brightened excitonic species.

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