Fine-tuning of the chemical structure of photoactive materials for highly efficient organic photovoltaics


The performance of organic photovoltaics is largely dependent on the balance of short-circuit current density (JSC) and open-circuit voltage (VOC). For instance, the reduction of the active materials’ optical bandgap, which increases the JSC, would inevitably lead to a concomitant reduction in VOC. Here, we demonstrate that careful tuning of the chemical structure of photoactive materials can enhance both JSC and VOC simultaneously. Non-fullerene organic photovoltaics based on a well-matched materials combination exhibit a certified high power conversion efficiency of 12.25% on a device area of 1 cm2. By combining Fourier-transform photocurrent spectroscopy and electroluminescence, we show the existence of a low but non-negligible charge transfer state as the possible origin of VOC loss. This study highlights that the reduction of the bandgap to improve the efficiency requires a careful materials design to minimize non-radiative VOC losses.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Chemical structures, and optical and electrochemical properties of the photoactive materials.
Fig. 2: Photovoltaic performance of devices based on different material combinations.
Fig. 3: Morphology of neat and blend films.
Fig. 4: Energy loss analysis.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.


  1. 1.

    Zhao, J. et al. Efficient organic solar cells processed from hydrocarbon solvents. Nat. Energy 1, 15027 (2016).

    Article  Google Scholar 

  2. 2.

    Li, S. et al. Energy-level modulation of small-molecule electron acceptors to achieve over 12% efficiency in polymer solar cells. Adv. Mater. 28, 9423–9429 (2016).

    Article  Google Scholar 

  3. 3.

    Zhao, F. et al. Single-junction binary-blend nonfullerene polymer solar cells with 12.1% efficiency. Adv. Mater. 29, 1700144 (2017).

    Article  Google Scholar 

  4. 4.

    Jiang, W. et al. Ternary nonfullerene polymer solar cells with 12.16% efficiency by introducing one acceptor with cascading energy level and complementary absorption. Adv. Mater. 30, 1703005 (2018).

    Article  Google Scholar 

  5. 5.

    Sun, C. et al. A low cost and high performance polymer donor material for polymer solar cells. Nat. Commun. 9, 743 (2018).

    Article  Google Scholar 

  6. 6.

    Xu, S. et al. A twisted thieno[3,4-b]thiophene-based electron acceptor featuring a 14-π-electron indenoindene core for high-performance organic photovoltaics. Adv. Mater. 29, 1704510 (2017).

    Article  Google Scholar 

  7. 7.

    Fan, Q. et al. Synergistic effect of fluorination on both donor and acceptor materials for high performance non-fullerene polymer solar cells with 13.5% efficiency. Sci. China Chem. 61, 531–537 (2018).

    Article  Google Scholar 

  8. 8.

    Xiao, Z., Jia, X. & Ding, L. Ternary organic solar cells offer 14% power conversion efficiency. Sci. Bull. 62, 1562–1564 (2017).

    Article  Google Scholar 

  9. 9.

    Xu, X. et al. Highly efficient ternary-blend polymer solar cells enabled by a nonfullerene acceptor and two polymer donors with a broad composition tolerance. Adv. Mater. 29, 1704271 (2017).

    Article  Google Scholar 

  10. 10.

    Fei, Z. et al. An alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor with high crystallinity exhibiting single junction solar cell efficiencies greater than 13% with low voltage losses. Adv. Mater. 30, 1705209 (2018).

    Article  Google Scholar 

  11. 11.

    Che, X., Li, Y., Qu, Y. & Forrest, S. R. High fabrication yield organic tandem photovoltaics combining vacuum- and solution-processed subcells with 15% efficiency. Nat. Energy 3, 422–427 (2018).

    Article  Google Scholar 

  12. 12.

    Huo, L. J. et al. Single-junction organic solar cells based on a novel wide-bandgap polymer with efficiency of 9.7%. Adv. Mater. 27, 2938 (2015).

    Article  Google Scholar 

  13. 13.

    Bin, H. et al. Non-fullerene polymer solar cells based on alkylthio and fluorine substituted 2D-conjugated polymers reach 9.5% efficiency. J. Am. Chem. Soc. 138, 4657–4664 (2016).

    Article  Google Scholar 

  14. 14.

    Fan, B. et al. High-performance nonfullerene polymer solar cells based on imide-functionalized wide-bandgap polymers. Adv. Mater. 29, 1606396 (2017).

    Article  Google Scholar 

  15. 15.

    Gao, H. et al. A new nonfullerene acceptor with near infrared absorption for high performance ternary-blend organic solar cells with efficiency over 13%. Adv. Sci. 5, 1800307 (2018).

    Article  Google Scholar 

  16. 16.

    Xiao, Z. et al. 26 mA cm−2 Jsc from organic solar cells with a low-bandgap nonfullerene acceptor. Sci. Bull. 62, 1494–1496 (2017).

    Article  Google Scholar 

  17. 17.

    Jia, B. et al. Breaking 10% efficiency in semitransparent solar cells with fused-undecacyclic electron acceptor. Chem. Mater. 30, 239–245 (2018).

    Article  Google Scholar 

  18. 18.

    Xie, S. et al. Effects of nonradiative losses at charge transfer states and energetic disorder on the open-circuit voltage in nonfullerene organic solar cells. Adv. Funct. Mater. 28, 1705659 (2018).

    Article  Google Scholar 

  19. 19.

    Li, N. et al. Abnormal strong burn-in degradation of highly efficient polymer solar cells caused by spinoidal donor-acceptor demixing. Nat. Commun. 8, 14541 (2017).

    Article  Google Scholar 

  20. 20.

    Zhang, C. et al. Overcoming the thermal instability of efficient polymer solar cells by employing novel fullerene-based acceptors. Adv. Energy Mater. 7, 1601204 (2017).

    Article  Google Scholar 

  21. 21.

    Zhao, W. et al. Molecular optimization enables over 13% efficiency in organic solar cells. J. Am. Chem. Soc. 139, 7148–7151 (2017).

    Article  Google Scholar 

  22. 22.

    Dai, S. et al. Fused nonacyclic electron acceptors for efficient polymer solar cells. J. Am. Chem. Soc. 139, 1336–1343 (2017).

    Article  Google Scholar 

  23. 23.

    Lan, L. et al. High-performance polymer solar cells based on a wide-bandgap polymer containing pyrrolo[3,4-f]benzotriazole-5,7-dione with a power conversion efficiency of 8.63%. Adv. Sci. 3, 1600032 (2016).

    Article  Google Scholar 

  24. 24.

    Meager, I. et al. Photocurrent enhancement from diketopyrrolopyrrole polymer solar cells through alkyl-chain branching point manipulation. J. Am. Chem. Soc. 135, 11537–11540 (2013).

    Article  Google Scholar 

  25. 25.

    Lin, Y. et al. An electron acceptor challenging fullerenes for efficient polymer solar cells. Adv. Mater. 27, 1170–1174 (2015).

    Article  Google Scholar 

  26. 26.

    Ghosh, S., Li, X. Q., Stepanenko, V. & Wurthner, F. Control of H- and J-type π stacking by peripheral alkyl chains and self-sorting phenomena in perylene bisimide homo- and heteroaggregates. Chem. Eur. J. 14, 11343–11357 (2008).

    Article  Google Scholar 

  27. 27.

    Chan, J. M. W., Tischler, J. R., Kooi, S. E., Bulovic, V. & Swager, T. M. Synthesis of J-aggregating dibenz[a,j]anthracene-based macrocycles. J. Am. Chem. Soc. 131, 5659–5666 (2009).

    Article  Google Scholar 

  28. 28.

    Würthner, F., Kaiser, T. E. & Saha-Möller, C. R. J-aggregates: from serendipitous discovery to supramolecular engineering of functional dye materials. Angew. Chem. Int. Ed. 50, 3376–3410 (2011).

    Article  Google Scholar 

  29. 29.

    Wu, Z. et al. n-Type water/alcohol-soluble naphthalene diimide-based conjugated polymers for high-performance polymer solar cells. J. Am. Chem. Soc. 138, 2004–2013 (2016).

    Article  Google Scholar 

  30. 30.

    Cheyns, D., Poortmans, J. & Heremans, P. Analytical model for the open-circuit voltage and its associated resistance in organic planar heterojunction solar cells. Phys. Rev. B 77, 165332 (2008).

    Article  Google Scholar 

  31. 31.

    Gasparini, N. et al. Designing ternary blend bulk heterojunction solar cells with reduced carrier recombination and a fill factor of 77%. Nat. Energy 1, 16118 (2016).

    MathSciNet  Article  Google Scholar 

  32. 32.

    Tang, Z., Tress, W. & Inganäs, O. Light trapping in thin film organic solar cells. Mater. Today 17, 389–396 (2014).

    Article  Google Scholar 

  33. 33.

    Raut, H. K., Ganesh, V. A., Nair, A. S. & Ramakrishna, S. Anti-reflective coatings: a critical, in-depth review. Energy Environ. Sci. 4, 3779 (2011).

    Article  Google Scholar 

  34. 34.

    Nikolis, V. C. et al. Reducing voltage losses in cascade organic solar cells while maintaining high external quantum efficiencies. Adv. Energy Mater. 7, 1700855 (2017).

    Article  Google Scholar 

  35. 35.

    Shockley, W. & Queisser, H. J. Detailed balance limit of efficiency of p–n junction solar cells. J. Appl. Phys. 32, 510–519 (1961).

    Article  Google Scholar 

  36. 36.

    Rau, U. Reciprocity relation between photovoltaic quantum efficiency and electroluminescent emission of solar cells. Phys. Rev. B 76, 085303 (2007).

    Article  Google Scholar 

  37. 37.

    Gao, F., Tress, W., Wang, J. & Inganas, O. Temperature dependence of charge carrier generation in organic photovoltaics. Phys. Rev. Lett. 114, 128701 (2015).

    Article  Google Scholar 

  38. 38.

    Zhao, W. et al. Fullerene-free polymer solar cells with over 11% efficiency and excellent thermal stability. Adv. Mater. 28, 4734–4739 (2016).

    Article  Google Scholar 

  39. 39.

    Baran, D. et al. Reduced voltage losses yield 10% efficient fullerene free organic solar cells with >1 V open circuit voltages. Energy Environ. Sci 9, 3783–3793 (2016).

    Article  Google Scholar 

  40. 40.

    Liu, X. et al. Efficient organic solar cells with extremely high open-circuit voltages and low voltage losses by suppressing nonradiative recombination losses. Adv. Energy Mater. 8, 1801699 (2018).

    Article  Google Scholar 

  41. 41.

    Vandewal, K. Interfacial charge transfer states in condensed phase systems. Annu. Rev. Phys. Chem. 67, 113–133 (2016).

    Article  Google Scholar 

  42. 42.

    Baran, D. et al. Role of polymer fractionation in energetic losses and charge carrier lifetimes of polymer: Fullerene solar cells. J. Phys. Chem. C 119, 19668–19673 (2015).

    Article  Google Scholar 

Download references


This work was financially supported by the Ministry of Science and Technology (no. 2014CB643501) and the National Natural Science Foundation of China (nos 91633301, 51521002, 51673069, 21520102006 and 21822505). N.L. gratefully acknowledges financial support from the DFG research grant BR 4031/13-1, the ETI funding at FAU Erlangen-Nürnberg, and the Bavarian Ministry of Economic Affairs and Media, Energy and Technology by funding the HI-ERN (IEK11) of FZ Jülich. C.J.B. gratefully acknowledges financial support through the ‘Aufbruch Bayern’ initiative of the state of Bavaria (EnCN and ‘Solar Factory of the Future’), the Bavarian Initiative ‘Solar Technologies go Hybrid’ (SolTech), the SFB 953 (DFG) and the Cluster of Excellence ‘Engineering of Advanced Materials’ (EAM) at FAU Erlangen-Nürnberg. RSoXS was performed at beamline and GIWAXS was performed at beamline 7.3.3 at the Advanced Light Source of Lawrence Berkeley National Laboratory (LBNL), which was supported by the DOE, Office of Science and Office of Basic Energy Sciences. We acknowledge the support for film sample preparation at the Molecular Foundry, LBNL. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under contract no. DE-AC02-05CH11231.

Author information




B.F., L.Y., N.L. and F.H. conceived the ideas and coordinated the work. B.F. and L.Y. designed the donor polymers. B.F. synthesized the polymers, conducted the ultraviolet–visible and cyclic voltammetric measurements, performed the device fabrication and characterization, and analysed the data. X.D. and X.T. conducted the FTPS and EL measurements. X.D. analysed the FTPS and EL data. X.T. performed the temperature-dependent J–V characterization. R.X. synthesized the acceptor molecules. F.L., W.Z., J.X. and W.M. conducted the GIWAXS measurements and analysed the data. F.L. and W.Z. performed the RSoXS measurements and analysed the data. K.A. performed the light-intensity-dependent J–V characterization. N.L. assisted with the large-area device fabrication and evaluation. B.F., L.Y., N.L., C.J.B., F.H. and Y.C. contributed to manuscript preparation. All authors commented on the manuscript.

Corresponding authors

Correspondence to Lei Ying or Ning Li or Fei Huang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary figures 1–18, Supplementary tables 1–10, Supplementary references

Reporting Summary

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Fan, B., Du, X., Liu, F. et al. Fine-tuning of the chemical structure of photoactive materials for highly efficient organic photovoltaics. Nat Energy 3, 1051–1058 (2018).

Download citation

Further reading