Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Perspective
  • Published:

Design strategies for organic semiconductors beyond the molecular formula

Nature Chemistry volume 4, pages 699–704 (2012)Cite this article

Subjects

Abstract

Organic semiconducting materials based on polymers and molecular systems containing an electronically delocalized structure are the basis of emerging optoelectronic technologies such as plastic solar cells and flexible transistors. For isolated molecules, guidelines exist that rely on the molecular formula to tailor the frontier (highest occupied or lowest unoccupied) molecular orbital energy levels and optical absorption profiles. Much less control can be achieved over relevant properties, however, as one makes the transition to the ensemble behaviour characteristic of the solid state. Polymeric materials are also challenging owing to the statistical description of the average number of repeat units. Here we draw attention to the limitations of molecular formulae as predictive tools for achieving properties relevant to device performances. Illustrative examples highlight the relevance of organization across multiple length scales, and how device performances — although relevant for practical applications — poorly reflect the success of molecular design.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Beyond the molecular level.
Figure 2: Molecular weight characteristics substantially influence performance in polymer electronic devices.
Figure 3: Methods for controlling intra- and intermolecular order and the influence on thin-film morphology or electronic properties.
Figure 4: Device performance of polymer and molecular samples with identical structures and similar molecular weight characteristics vary widely as a result of different processing conditions.

Similar content being viewed by others

References

  1. Nozik, A. J. & Miller, J. Introduction to solar photon conversion. Chem. Rev. 110, 6443–6445 (2010).

    Article  CAS  Google Scholar 

  2. Mishra, A. & Bäuerle, P. Small molecule organic semiconductors on the move: Promises for future solar energy technology. Angew. Chem. Int. Ed. 51, 2020–2067 (2012).

    Article  CAS  Google Scholar 

  3. Roncali, J. Molecular bulk heterojunctions: An emerging approach to organic solar cells. Acc. Chem. Res. 42, 1719–1730 (2009).

    Article  CAS  Google Scholar 

  4. Cheng, Y. J., Yang, S. H. & Hsu, C. S. Synthesis of conjugated polymers for organic solar cell applications. Chem. Rev. 109, 5868–5923 (2009).

    Article  CAS  Google Scholar 

  5. Beaujuge, P. M. & Fréchet, J. M. J. Molecular design and ordering effects in π-functional materials for transistor and solar cell applications. J. Am. Chem. Soc. 133, 20009–20029 (2011).

    Article  CAS  Google Scholar 

  6. Gendron, D. & Leclerc, M. New conjugated polymers for organic solar cells. Energy Environ. Sci. 4, 1225–1237 (2011).

    Article  CAS  Google Scholar 

  7. Zhou, H., Yang, L. & You, W. Rational design of high performance conjugated polymers for organic solar cells. Macromolecules 45, 607–632 (2012).

    Article  CAS  Google Scholar 

  8. Facchetti, A. π-Conjugated polymers for organic electronics and photovoltaic cell applications. Chem. Mater. 23, 733–758 (2010).

    Article  Google Scholar 

  9. Tsao, H. N. et al. Ultrahigh mobility in polymer field-effect transistors by design. J. Am. Chem. Soc. 133, 2605–2612 (2011).

    Article  CAS  Google Scholar 

  10. Leong, W. L. et al. Role of trace impurities in the photovoltaic performance of solution processed small-molecule bulk heterojunction solar cells. Chem. Sci. 3, 2103–2109 (2012).

    Article  CAS  Google Scholar 

  11. Nielsen, K. T., Bechgaard, K. & Krebs, F. C. Removal of palladium nanoparticles from polymer materials. Macromolecules 38, 658–659 (2005).

    Article  CAS  Google Scholar 

  12. Wang, S., Kiersnowski, A., Pisula, W. & Müllen, K. Microstructure evolution and device performance in solution-processed polymeric field-effect transistors: The Key role of the first monolayer. J. Am. Chem. Soc. 134, 4015–4018 (2012).

    Article  CAS  Google Scholar 

  13. Peet, J. et al. Efficiency enhancement in low-bandgap polymer solar cells by processing with alkane dithiols. Nature Mater. 6, 497–500 (2007).

    Article  CAS  Google Scholar 

  14. Steim, R., Kogler, F. R. & Brabec, C. J. Interface materials for organic solar cells. J. Mater. Chem. 20, 2499–2512 (2010).

    Article  CAS  Google Scholar 

  15. Hoeben, F. J. M., Jonkheijm, P., Meijer, E. W. & Schenning, A. P. H. J. About supramolecular assemblies of π-conjugated systems. Chem. Rev. 105, 1491–1546 (2005).

    Article  CAS  Google Scholar 

  16. Giridharagopal, R. & Ginger, D. S. Characterizing morphology in bulk heterojunction organic photovoltaic systems. J. Phys. Chem. Lett. 1, 1160–1169 (2010).

    Article  CAS  Google Scholar 

  17. Coffin, R. C., Peet, J., Rogers, J. & Bazan, G. C. Streamlined microwave-assisted preparation of narrow-bandgap conjugated polymers for high-performance bulk heterojunction solar cells. Nature Chem. 1, 657–661 (2009).

    Article  CAS  Google Scholar 

  18. Okamoto, K. & Luscombe, C. K. Controlled polymerizations for the synthesis of semiconducting conjugated polymers. Polym. Chem. 2, 2424–2434 (2011).

    Article  CAS  Google Scholar 

  19. Carsten, B., He, F., Son, H. J., Xu, T. & Yu, L. Stille polycondensation for synthesis of functional materials. Chem. Rev. 111, 1493–1528 (2011).

    Article  CAS  Google Scholar 

  20. Berrouard, P. et al. Synthesis of 5-alkyl[3,4-c]thienopyrrole-4,6-dione-based polymers by direct heteroarylation. Angew. Chem. Int. Ed. 51, 2068–2071 (2012).

    Article  CAS  Google Scholar 

  21. Osaka, I. & McCullough, R. D. Advances in molecular design and synthesis of regioregular polythiophenes. Acc. Chem. Res. 41, 1202–1214 (2008).

    Article  CAS  Google Scholar 

  22. Kline, R. J., McGehee, M. D., Kadnikova, E. N., Liu, J. & Fréchet, J. M. J. Controlling the field-effect mobility of regioregular polythiophene by changing the molecular weight. Adv. Mater. 15, 1519–1522 (2003).

    Article  CAS  Google Scholar 

  23. Jeffries-El, M., Sauvé, G. & McCullough, R. D. In-situ end-group functionalization of regioregular poly(3-alkylthiophene) using the Grignard metathesis polymerization method. Adv. Mater. 16, 1017–1019 (2004).

    Article  CAS  Google Scholar 

  24. Kim, Y. et al. Effect of the end group of regioregular poly(3-hexylthiophene) polymers on the performance of polymer/fullerene solar cells. J. Phys. Chem. C 111, 8137–8141 (2007).

    Article  CAS  Google Scholar 

  25. Park, J. K. et al. End-capping effect of a narrow bandgap conjugated polymer on bulk heterojunction solar cells. Adv. Mater. 23, 2430–2435 (2011).

    Article  CAS  Google Scholar 

  26. Kim, J. S. et al. High-efficiency organic solar cells based on end-functional-group-modified poly(3-hexylthiophene). Adv. Mater. 22, 1355–1360 (2010).

    Article  CAS  Google Scholar 

  27. Sirringhaus, H. et al. Two-dimensional charge transport in self-organized, high-mobility conjugated polymers. Nature 401, 685–688 (1999).

    Article  CAS  Google Scholar 

  28. Kim, Y. et al. A strong regioregularity effect in self-organizing conjugated polymer films and high-efficiency polythiophene:fullerene solar cells. Nature Mater. 5, 197–203 (2006).

    Article  CAS  Google Scholar 

  29. Ying, L. et al. Regioregular pyridal[2,1,3]thiadiazole π-conjugated copolymers. J. Am. Chem. Soc. 133, 18538–18541 (2011).

    Article  CAS  Google Scholar 

  30. McCulloch, I. et al. Liquid-crystalline semiconducting polymers with high charge-carrier mobility. Nature Mater. 5, 328–333 (2006).

    Article  CAS  Google Scholar 

  31. Chabinyc, M. L., Toney, M. F., Kline, R. J., McCulloch, I. & Heeney, M. X-ray scattering study of thin films of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene). J. Am. Chem. Soc. 129, 3226–3237 (2007).

    Article  CAS  Google Scholar 

  32. Gidron, O., Diskin-Posner, Y. & Bendikov, M. α-Oligofurans. J. Am. Chem. Soc. 132, 2148–2150 (2010).

    Article  CAS  Google Scholar 

  33. Patra, A. & Bendikov, M. Polyselenophenes. J. Mater. Chem. 20, 422–433 (2010).

    Article  CAS  Google Scholar 

  34. Jahnke, A. A. & Seferos, D. S. Polytellurophenes. Macromol. Rapid Commun. 32, 943–951 (2011).

    Article  CAS  Google Scholar 

  35. Chen, H. Y. et al. Silicon atom substitution enhances interchain packing in a thiophene-based polymer system. Adv. Mater. 22, 371–375 (2010).

    Article  CAS  Google Scholar 

  36. Scharber, M. C. et al. Influence of the bridging atom on the performance of a low-bandgap bulk heterojunction solar cell. Adv. Mater. 22, 367–370 (2010).

    Article  CAS  Google Scholar 

  37. Amb, C. M. et al. Dithienogermole as a fused electron donor in bulk heterojunction solar cells. J. Am. Chem. Soc. 133, 10062–10065 (2011).

    Article  CAS  Google Scholar 

  38. Dang, M. T., Hirsch, L. & Wantz, G. P3HT:PCBM, best seller in polymer photovoltaic research. Adv. Mater. 23, 3597–3602 (2011).

    Article  CAS  Google Scholar 

  39. Piliego, C. et al. Synthetic control of structural order in N-alkylthieno[3,4-c]pyrrole-4,6-dione-based polymers for efficient solar cells. J. Am. Chem. Soc. 132, 7595–7597 (2010).

    Article  CAS  Google Scholar 

  40. Zou, Y. et al. A thieno[3,4-c]pyrrole-4,6-dione-based copolymer for efficient solar cells. J. Am. Chem. Soc. 132, 5330–5331 (2010).

    Article  CAS  Google Scholar 

  41. Zhang, Y. et al. Efficient polymer solar cells based on the copolymers of benzodithiophene and thienopyrroledione. Chem. Mater. 22, 2696–2698 (2010).

    Article  CAS  Google Scholar 

  42. Peet, J., Senatore, M. L., Heeger, A. J. & Bazan, G. C. The role of processing in the fabrication and optimization of plastic solar cells. Adv. Mater. 21, 1521–1527 (2009).

    Article  CAS  Google Scholar 

  43. Aida, T., Meijer, E. W. & Stupp, S. I. Functional supramolecular polymers. Science 335, 813–817 (2012).

    Article  CAS  Google Scholar 

  44. Würthner, F. & Meerholz, K. Systems chemistry approach in organic photovoltaics. Chem. Eur. J. 16, 9366–9373 (2010).

    Article  Google Scholar 

  45. Sun, Y. et al. Solution-processed small-molecule solar cells with 6.7% efficiency. Nature Mater. 11, 44–48 (2012).

    Article  CAS  Google Scholar 

  46. Henson, Z. B., Welch, G. C., van der Poll, T. & Bazan, G. C. Pyridalthiadiazole-based narrow band gap chromophores. J. Am. Chem. Soc. 134, 3766–3779 (2012).

    Article  CAS  Google Scholar 

  47. Fitzner, R. et al. Interrelation between crystal packing and small-molecule organic solar cell performance. Adv. Mater. 24, 675–680 (2012).

    Article  CAS  Google Scholar 

  48. Tong, M. et al. Higher molecular weight leads to improved photoresponsivity, charge transport and interfacial ordering in a narrow bandgap semiconducting polymer. Adv. Funct. Mater. 20, 3959–3965 (2010).

    Article  CAS  Google Scholar 

  49. Herzing, A. A., Richter, L. J. & Anderson, I. M. 3D nanoscale characterization of thin-film organic photovoltaic device structures via spectroscopic contrast in the TEM 1. J. Phys. Chem. C 114, 17501–17508 (2010).

    Article  CAS  Google Scholar 

  50. Hammond, M. R. et al. Molecular order in high-efficiency polymer/fullerene bulk heterojunction solar cells. ACS Nano 5, 8248–8257 (2011).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

Work done at UCSB has been supported through the NSF (DMR 1005546). We gratefully thank Peter Allen for assistance with image preparation.

Author information

Authors and Affiliations

  1. Department of Chemistry & Biochemistry, Department of Materials, Center for Polymers and Organic Solids, University of California Santa Barbara, 93106, California, USA

    Zachary B. Henson & Guillermo C. Bazan

  2. Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, D-55021, Germany

    Klaus Müllen

Authors
  1. Zachary B. Henson
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Klaus Müllen
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Guillermo C. Bazan
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding authors

Correspondence to Klaus Müllen or Guillermo C. Bazan.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Henson, Z., Müllen, K. & Bazan, G. Design strategies for organic semiconductors beyond the molecular formula. Nature Chem 4, 699–704 (2012). https://doi.org/10.1038/nchem.1422

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nchem.1422

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing