Abstract
An optical dyadic Green's function framework to describe the transverse electromagnetic fields in a planar perovskite solar-cell stack is coupled to an electronic drift-diffusion model for rigorous treatment of photon recycling in the wave-optics regime for a realistic photovoltaic device. The optical model provides the local reabsorption rate as well as a detailed-balance compatible radiative prefactor, which are used in the electronic model to achieve a self-consistent solution that yields the full optoelectronic device characteristics. The presented approach provides detailed insights into the impact of photon recycling on device performance under different regimes of charge transport and recombination and can help identify the various electronic and optical losses for nonideal, realistic devices. The global efficiency of photon recycling is quantified by defining quantum efficiencies of reabsorbed radiation, while the local efficiency can furthermore be quantified by defining an effective local radiative prefactor. The model introduced here can be used to guide the design of future devices that exploit the full potential of photon recycling.
Highlights
In the past few years, hybrid metal-halide perovskite materials have become more and more popular for use in single-junction and multijunction solar cells, especially in combination with crystalline silicon, where for both device architectures new record efficiencies could be reached recently (>25% for single-junction [1] and >29% for Si tandem cells [2])
As model systems the two high-VOC device architectures presented by Liu et al [32] are implemented, which both consist of an indium tin oxide (ITO) transparent electrode (150 nm), polytriarylamine (PTAA) as hole transport layer (HTL, 30/12 nm), a methylammonium lead iodide (MAPI) perovskite absorber layer (280/510 nm) and phenyl-C61butyric acid methyl ester (PCBM) as electron transport layer (ETL, 45 nm)
It is interesting to note that these quantum efficiencies are not necessarily always higher for lower nonradiative recombination, as for both devices the quantum efficiencies in the radiative limit temporarily fall short compared to the SRH case
Summary
In the past few years, hybrid metal-halide perovskite materials have become more and more popular for use in single-junction and multijunction (tandem) solar cells, especially in combination with crystalline silicon, where for both device architectures new record efficiencies could be reached recently (>25% for single-junction [1] and >29% for Si tandem cells [2]). Treatments of PR beyond the ray-optical approximation in thin-film perovskite devices have been limited to purely optical estimates of the open-circuit voltage enhancement using either a detailed-balance approach [9,14,15] or a rigorous solution of Maxwell’s equations in the dipole picture [16,17] for external and internal emission. The full coupling of a wave-optical treatment of emission and reabsorption to the electronic transport problem beyond the radiative limit in a detailed-balance compatible way has not been achieved so far, as would be needed for a correct understanding of this phenomenon in thin-film perovskite solar cells. The paper is wrapped up with a summary and conclusion of the findings
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