Harnessing singlet exciton fission to break the Shockley–Queisser limit

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Singlet exciton fission is a carrier multiplication process in organic semiconductors that generates two electron–hole pairs for each photon absorbed. Singlet fission occurs on sub-100 fs timescales with yields of up to 200%, and photovoltaic devices based on singlet fission have achieved external quantum efficiencies above 100%. The major challenge for the field is to use singlet fission to improve the efficiency of conventional inorganic solar cells, such as silicon, and to break the Shockley–Queisser limit on the efficiency of single-junction photovoltaics. Achieving this goal requires a broader and more collaborative effort than the one used at present. Synthetic chemists, spectroscopists, theorists, materials scientists, device physicists and engineers will need to work together. In this Review, we critically assess the current status of the field, highlight the key results and identify the challenges ahead. In doing so, we seek to open the field to new expertise and ideas, which will in turn promote both fundamental science and device applications.

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Figure 1: The losses in an ideal silicon cell leading to the Shockley–Queisser limit.
Figure 2: The basic concept of singlet exciton fission.
Figure 3: Experimental detection of singlet exciton fission.
Figure 4: The mechanism of singlet exciton fission.
Figure 5: The concepts and schematics of devices enhanced by singlet exciton fission.
Figure 6: A schematic of the proposed singlet fission photon multiplier device.


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A.R. and R.H.F. thank M. Taybjee and J. Allardice for help with preparing Fig. 3b,c. A.R. and R.H.F. thank the Engineering and Physical Sciences Research Council (EPSRC) and the Winton Programme for the Physics of Sustainability for funding.

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A.R. obtained the data for the article. Both authors made substantial contributions to the content, wrote the manuscript and reviewed and/or edited the manuscript before submission.

Correspondence to Akshay Rao.

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Rao, A., Friend, R. Harnessing singlet exciton fission to break the Shockley–Queisser limit. Nat Rev Mater 2, 17063 (2017) doi:10.1038/natrevmats.2017.63

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