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Energy conversion approaches and materials for high-efficiency photovoltaics

Abstract

The past five years have seen significant cost reductions in photovoltaics and a correspondingly strong increase in uptake, with photovoltaics now positioned to provide one of the lowest-cost options for future electricity generation. What is becoming clear as the industry develops is that area-related costs, such as costs of encapsulation and field-installation, are increasingly important components of the total costs of photovoltaic electricity generation, with this trend expected to continue. Improved energy-conversion efficiency directly reduces such costs, with increased manufacturing volume likely to drive down the additional costs associated with implementing higher efficiencies. This suggests the industry will evolve beyond the standard single-junction solar cells that currently dominate commercial production, where energy-conversion efficiencies are fundamentally constrained by Shockley–Queisser limits to practical values below 30%. This Review assesses the overall prospects for a range of approaches that can potentially exceed these limits, based on ultimate efficiency prospects, material requirements and developmental outlook.

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Figure 1: Light absorption and emission, SQ limits, experimental energy-conversion efficiencies, radiative efficiencies and sunlight incident angles.
Figure 2: Multiple-junction cells, efficiency limits and highest experimental results.
Figure 3: Sub-bandgap absorption processes, equivalent circuit and limiting efficiencies.
Figure 4: Photon wavelength manipulation using luminescent concentrators and photon up- and down-conversion.
Figure 5: Schemes in which a single photon creates multiple photogenerated carriers.
Figure 6: Solar thermal conversion and conversion efficiencies.
Figure 7: Approaches that are thermodynamically related to solar thermal conversion.
Figure 8: Alternative high-efficiency approaches.

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The authors acknowledge support from the Australian Government through the Australian Renewable Energy Agency (ARENA). The Australian Government does not accept responsibility for any information or advice contained herein.

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Green, M., Bremner, S. Energy conversion approaches and materials for high-efficiency photovoltaics. Nature Mater 16, 23–34 (2017). https://doi.org/10.1038/nmat4676

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