Skip to main content

Thank you for visiting 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.

  • Article
  • Published:

Activating efficient phosphorescence from purely organic materials by crystal design

An Addendum to this article was published on 15 March 2011

This article has been updated


Phosphorescence is among the many functional features that, in practice, divide pure organic compounds from organometallics and inorganics. Considered to be practically non-phosphorescent, purely organic compounds (metal-free) are very rarely explored as emitters in phosphor applications, despite the emerging demand in this field. To defy this paradigm, we describe novel design principles to create purely organic materials demonstrating phosphorescence that can be turned on by incorporating halogen bonding into their crystals. By designing chromophores to contain triplet-producing aromatic aldehydes and triplet-promoting bromine, crystal-state halogen bonding can be made to direct the heavy atom effect to produce surprisingly efficient solid-state phosphorescence. When this chromophore is diluted into the crystal of a bi-halogenated, non-carbonyl analogue, ambient phosphorescent quantum yields reach 55%. Here, using this design, a series of pure organic phosphors are colour-tuned to emit blue, green, yellow and orange. From this initial discovery, a directed heavy atom design principle is demonstrated that will allow for the development of bright and practical purely organic phosphors.

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

Access options

Buy this article

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

Figure 1: Directed heavy atom organic phosphorescence and its design principle.
Figure 2: Photophysical properties of Br6A (1).
Figure 3: Dependence of emission on crystal growth.
Figure 4: Photophysical properties of mixed crystals of Br6A (1) and Br6 (2).
Figure 5: Photophysical properties of colour-tuned aromatic aldehydes.

Similar content being viewed by others

Change history

  • 15 March 2011

    After the publication of this Article the authors found a further relevant paper that they would like to cite. The paper reports crystallization-induced rotational restriction of benzophenone derivatives and ensuing phosphorescence enhancement: Yuan, W. Z. et al. Crystallization-induced phosphorescence of pure organic luminogens at room temperature. J. Phys. Chem. C 114, 6090–6099 (2010).


  1. Turro, N. J. Modern Molecular Photochemistry 99–100 (University Science Books, 1991).

  2. Hoshino, S. & Suzuki, H. Electroluminescence from triplet excited states of benzophenone. Appl. Phys. Lett. 69, 224–226 (1996).

    Article  CAS  Google Scholar 

  3. Kohler, A., Wilson, J. S. & Friend, R. H. Fluorescence and phosphorescence in organic materials. Adv. Mater. 14, 701–707 (2002).

    Article  CAS  Google Scholar 

  4. Baldo, M. A. et al. Highly efficient phosphorescent emission from organic electroluminescent devices. Nature 395, 151–154 (1998).

    Article  CAS  Google Scholar 

  5. Shao, Y. & Yang, Y. Efficient organic heterojunction photovoltaic cells based on triplet materials. Adv. Mater. 17, 2841–2844 (2005).

    Article  CAS  Google Scholar 

  6. de Silva, A. P. et al. Signaling recognition events with fluorescent sensors and switches. Chem. Rev. 97, 1515–1566 (1997).

    Article  CAS  Google Scholar 

  7. Rumsey, W. L., Vanderkooi, J. M. & Wilson, D. F. Imaging of phosphorescence: a novel method for measuring oxygen distribution in perfused tissue. Science 241, 1649–1651 (1988).

    Article  CAS  Google Scholar 

  8. Zhang, G., Palmer, G. M., Dewhirts, M. W. & Fraser, C. L. A dual-emissive-materials design concept enables tumour hypoxia imaging. Nature Mater. 8, 747–751 (2009).

    Article  CAS  Google Scholar 

  9. Wong, W.-Y. & Ho, C.-L. Functional metallophosphors for effective charge carrier injections/transport: new robust OLED materials with emerging applications. J. Mater. Chem. 19, 4437–4640 (2009).

    Article  Google Scholar 

  10. You Y. & Park, S. Y. Phosphorescent iridium(III) complexes: toward high phosphorescence quantum efficiency through ligand control. Dalton Trans. 8, 1253–1472 (2009).

    Google Scholar 

  11. Kearns, D. R. & Case, W. A. Investigation of singlet–triplet transitions by the phosphorescence excitation method. III. Aromatic ketones and aldehydes. J. Am. Chem. Soc. 88, 5087–5097 (1966).

    Article  CAS  Google Scholar 

  12. Itoh, T. The evidence showing that the intersystem crossing yield of benzaldehyde vapour is unity. Chem. Phys. Lett. 151, 166–168 (1988).

    Article  CAS  Google Scholar 

  13. Clark, W. D. K., Litt, A. D. & Steel, C. Triplet lifetimes of benzophenone, acetophenone, and triphenylene in hydrocarbons. J. Am. Chem. Soc. 91, 5413–5415 (1969).

    Article  CAS  Google Scholar 

  14. Parker, C. A. & Joyce, T. A. Phosphorescence of benzophenone in fluid solution. Chem. Commun. 749–750 (1968).

  15. Turro, N. J. Modern Molecular Photochemistry 116–117 (University Science Books, 1991).

  16. Giachino, G. G & Kearns, D. R. Nature of the external heavy-atom effect on radiative and nonradiative singlet–triplet transitions. J. Chem Phys. 52, 2964–2974 (1970).

    Article  CAS  Google Scholar 

  17. Saigusa, H. & Azumi, T. Internal heavy atom effect on the triplet spin sublevels of the lowest triplet state of naphthalene. I. Radiative and non radiative decays of the spin sublevels of 1- halonaphthalenes. J. Chem. Phys. 71, 1408–1413 (1979).

    Article  CAS  Google Scholar 

  18. Turro, N. J. Modern Molecular Photochemistry 125–126 (University Science Books, 1991).

  19. Hassel, O. Structural aspects of interatomic charge-transfer bonding, Nobel Lecture, 9 June 1970.

  20. Auffinger, P., Hays, F. A., Westhof, E. & Ho, P. S. Halogen bonds in biological molecules. Proc. Natl Acad. Sci. USA 101, 16789–16794 (2004).

    Article  CAS  Google Scholar 

  21. Metrangolo, P. & Resnati, G. Halogen bonding: a paradigm in supramolecular chemistry. Chem. Eur. J. 7, 2511–2519 (2001).

    Article  CAS  Google Scholar 

  22. Roy, S. & Matzger, A. J. Unmasking a third polymorph of a benchmark crystal-structure-prediction compound. Angew. Chem. 121, 8657–8660 (2009).

    Article  Google Scholar 

  23. Fischer, M. & Georges, J. Fluorescence quantum yield of rhodamine 6G in ethanol as a function of concentration using thermal lens spectrometry. Chem. Phys. Lett. 260, 115–118 (1996).

    Article  CAS  Google Scholar 

Download references


The authors thank J.W. Kampf, S. Lin and K. Noon for critical services. The initial discovery of the presented phosphorescence was made while we were conducting a project supported by a National Science Foundation (NSF) CAREER Award (DMR 0644864). This work was partly supported by a WCU (World Class University) program through National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (R31-2008-000-10075-0).

Author information

Authors and Affiliations



O.B. synthesized all materials and crystals, made all photophysical measurements and analyses presented, and wrote the paper. K.L. made the initial discovery of phosphorescence. H.-J.K. assisted in early optical analyses. K.Y.L. conducted high-performance liquid chromatography to identify the aldehyde structure. J.K designed and supervised the research and oversaw the writing of the paper.

Corresponding author

Correspondence to Jinsang Kim.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 929 kb)

Supplementary information

Supplementary movie S2 (MPG 27160 kb)

Supplementary information

Crystallographic data for compound 1 (Br6A) (CIF 13 kb)

Supplementary information

Crystallographic data for compound 2 (Br6) (CIF 10 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Bolton, O., Lee, K., Kim, HJ. et al. Activating efficient phosphorescence from purely organic materials by crystal design. Nature Chem 3, 205–210 (2011).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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