Energy loss within organic solar cells (OSCs) is undesirable as it reduces cell efficiency1,2,3,4. In particular, non-radiative recombination loss3 and energetic disorder5, which are closely related to the tail states below the band edge and the overall photon energy loss, need to be minimized to improve cell performance. Here, we report how the use of a small-molecule acceptor with torsion-free molecular conformation can achieve a very low degree of energetic disorder and mitigate energy loss in OSCs. The resulting single-junction OSC has an energy loss due to non-radiative recombination of just 0.17 eV and a high power conversion efficiency of up to 16.54% (certified as 15.89% by the National Renewable Energy Laboratory). The findings take studies of organic photovoltaics deeper into a new regime, beyond the limits of energetic disorder and large energy offset for charge generation.
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The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request. Raw data essential to the work are available online as Source Data files.
Computer code used to generate results (to calculate the spontaneous emission rate, simulate maximum open-circuit voltage, generate fits to the spectral features in EL spectra) for this study is available from the corresponding author (H.W.) upon request.
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H.W. thanks the National Natural Science Foundation of China for financial support (no. 51521002). Y.Z. acknowledges the National Natural Science Foundation of China (no. 21875286), the National Key Research & Development Projects of China (no. 2017YFA0206600) and the Science Fund for Distinguished Young Scholars of Hunan Province (2017JJ1029). Z.H. acknowledges the National Natural Science Foundation of China for financial support (nos. 51622302 and 21733005). We thank T. Song and H. Meng for solar cell performance verification, J. Zhang for acquiring GIWAXS analysis and B. Xiao for temperature-dependent current–voltage characteristics measurements. We thank S. Bilson for proof reading.
The authors declare no competing interests.
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Extended Data Fig. 1 The context page of test report by the National Renewable Energy Laboratory (NREL).
a, The test summary for a champion cell (#892-b) tested under the initial asymptotic scan. The asymptotic scan was measured through holding the device at the bias near the maximal power condition. b, The test summary for the cell tested in the second round asymptotic scan. c, The test summary for the cell tested under the standard sweep condition. Source data
Device parameters of representative devices from various photovoltaic material systems in literature are also included for comparison.
Absorbance spectra Source Data.
Current density–voltage (J–V) characteristics and EQE spectra Source Data of the best-performing OSCs.
The measured EL spectrum, the experimental EQE spectrum and the deduced EQE spectrum determined from the EL spectrum Source Data.
Test report by NREL Source Data.
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Liu, S., Yuan, J., Deng, W. et al. High-efficiency organic solar cells with low non-radiative recombination loss and low energetic disorder. Nat. Photonics 14, 300–305 (2020). https://doi.org/10.1038/s41566-019-0573-5
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