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.

  • Article
  • Published:

X-ray imaging with scintillator-sensitized hybrid organic photodetectors

Nature Photonics volume 9, pages 843–848 (2015)Cite this article

Subjects

This article has been updated

Abstract

Medical X-ray imaging requires cost-effective and high-resolution flat-panel detectors for the energy range between 20 and 120 keV. Solution-processed photodetectors provide the opportunity to fabricate detectors with a large active area at low cost. Here, we present a disruptive approach that improves the resolution of such detectors by incorporating terbium-doped gadolinium oxysulfide scintillator particles into an organic photodetector matrix. The X-ray induced light emission from the scintillators is absorbed within hundreds of nanometres, which is negligible compared with the pixel size. Hence, optical crosstalk, a limiting factor in the resolution of scintillator-based X-ray detectors, is minimized. The concept is validated with a 256 × 256 pixel detector with a resolution of 4.75 lp mm−1 at a MTF = 0.2, significantly better than previous stacked scintillator-based flat-panel detectors. We achieved a resolution that proves the feasibility of solution-based detectors in medical applications. Time-resolved electrical characterization showed enhanced charge carrier mobility with increased scintillator filling, which is explained by morphological changes.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

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

Figure 1: Hybrid organic X-ray image sensor.
Figure 2: Influence of scintillator fraction on layer morphology.
Figure 3: Optoelectronical properties of HPDs.
Figure 4: Mobility and morphology characteristics.

Similar content being viewed by others

Change history

  • 13 November 2015

    In the version of this Article originally published online, the following affiliation for the author Oier Bikondoa had not been included: Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK. This has now been added and the subsequent affiliation renumbered in all versions of the Article.

References

  1. Spahn, M. Flat detectors and their clinical applications. Eur. Radiol. 15, 1934–1947 (2005).

    Article  Google Scholar 

  2. Pacella, D. Energy-resolved X-ray detectors: the future of diagnostic imaging. Rep.Med. Imag. 8, 1–13 (2015).

    Google Scholar 

  3. Kabir, M. Z. et al. Direct conversion x-ray sensors: Sensitivity, DQE and MTF. IEEE Proc. Circ. Dev. Syst. 150, 258–266 (2003).

    Article  Google Scholar 

  4. Zhao, W., Ristic, G. & Rowlands, J. A. X-ray imaging performance of structured cesium iodide scintillators. Med. Phys. 31, 2594–2605 (2004).

    Article  Google Scholar 

  5. Pin, Y., Harmon, C. D., Doty, F. P. & Ohlhausen, J. A. Effect of humidity on scintillation performance in Na and Tl activated CsI crystals. IEEE Trans. Nucl. Sci. 61, 1024–1031 (2014).

    Article  ADS  Google Scholar 

  6. Kasap, S. et al. Amorphous and polycrystalline photoconductors for direct conversion flat panel x-ray image sensors. Sensors 11, 5112–5157 (2011).

    Article  Google Scholar 

  7. Kabir, M. Z. et al. Effect of repeated x-ray exposure on the resolution of amorphous selenium based x-ray imagers. Med. Phys. 37, 1339–1349 (2010).

    Article  Google Scholar 

  8. Kasap, S. O. X-ray sensitivity of photoconductors: application to stabilized a-Se. J. Phys. D 33, 2853–2865 (2000).

    Article  ADS  Google Scholar 

  9. Gelinck, G. H. et al. X-ray imager using solution processed organic transistor arrays and bulk heterojunction photodiodes on thin, flexible plastic substrate. Org. Electron. 14, 2602–2609 (2013).

    Article  Google Scholar 

  10. Tedde, S. F. et al. Fully spray coated organic photodiodes. Nano Lett. 9, 980–983 (2009).

    Article  ADS  Google Scholar 

  11. Krebs, F. C. et al. A round robin study of flexible large-area roll-to-roll processed polymer solar cell modules. Sol. Energy Mater. Sol. Cells 93, 1968–1977 (2009).

    Article  Google Scholar 

  12. Brabec, C. J. et al. Polymer–fullerene bulk-heterojunction solar cells. Adv. Mater. 22, 3839–3856 (2009).

    Article  ADS  Google Scholar 

  13. Kraabel, B. et al. Ultrafast photoinduced electron transfer in conducting polymer buckminsterfullerene composites. Chem. Phys. Lett. 213, 389–394 (1993).

    Article  ADS  Google Scholar 

  14. Heeger, A. J. 25th anniversary article: bulk heterojunction solar cells: understanding the mechanism of operation. Adv. Mater. 26, 10–28 (2014).

    Article  Google Scholar 

  15. Brabec, C. J., Sariciftci, N. S. & Hummelen, J. C. Plastic solar cells. Adv. Funct. Mater. 11, 15–26 (2001).

    Article  Google Scholar 

  16. Rauch, T. et al. Near-infrared imaging with quantum-dot-sensitized organic photodiodes. Nature Photon. 3, 332–336 (2009).

    Article  ADS  Google Scholar 

  17. Mills, C. A. et al. Enhanced x-ray detection sensitivity in semiconducting polymer diodes containing metallic nanoparticles. J. Phys. D 46, 275102 (2013).

    Article  ADS  Google Scholar 

  18. Street, R. A., Northrup, J. E. & Krusor, B. S. Radiation induced recombination centers in organic solar cells. Phys. Rev. B 85, 205211 (2012).

    Article  ADS  Google Scholar 

  19. Samei, E., Flynn, M. J. & Reimann, D. A. A method for measuring the presampled MTF of digital radiographic systems using an edge test device. Med. Phys. 25, 102–113 (1998).

    Article  Google Scholar 

  20. International Commission on Radiation Units. Patient dosimetry for X rays used in medical imaging. J. ICRU 5, http://dx.doi.org/10.1093/jicru/ndi016 (2005).

  21. Chen, H.-Y., LoMichael, K. F., Yang, G., Monbouquette, H. G. & Yang, Y. Nanoparticle-assisted high photoconductive gain in composites of polymer and fullerene. Nature Nanotech. 3, 543–547 (2008).

    Article  ADS  Google Scholar 

  22. Fowler, R. H. & Nordheim, L. Electron Emission in Intense Electric Fields (Royal Society, 1928).

    Book  Google Scholar 

  23. Heeger, A. J., Parker, I. D. & Yang, Y. Carrier injection into semiconducting polymers: Fowler-Nordheim field-emission tunneling. Synthetic Met. 67, 23–29 (1994).

    Article  Google Scholar 

  24. Oehzelt, M., Koch, N. & Heimel, G. Organic semiconductor density of states controls the energy level alignment at electrode interfaces. Nature Commun. 5, 4174 (2014).

    Article  ADS  Google Scholar 

  25. Vázquez, H. et al. Barrier formation at metal organic interfaces: dipole formation and the charge neutrality level. Appl. Surf. Sci. 234, 107–112 (2004).

    Article  ADS  Google Scholar 

  26. Büchele, P. et al. Space charge region effects in bidirectional illuminated P3HT: PCBM bulk heterojunction photodetectors. Org. Electron. 22, 29–34 (2015).

    Article  Google Scholar 

  27. Saracco, E. et al. Work function tuning for high-performance solution-processed organic photodetectors with inverted structure. Adv. Mater. 25, 6534–6538 (2013).

    Article  Google Scholar 

  28. Mozer, A. J. et al. Charge transport and recombination in bulk heterojunction solar cells studied by the photoinduced charge extraction in linearly increasing voltage technique. Appl. Phys. Lett. 86, 112104 (2005).

    Article  ADS  Google Scholar 

  29. Juška, G. et al. Extraction current transients: new method of study of charge transport in microcrystalline silicon. Phys. Rev. Lett. 84, 4946 (2000).

    Article  ADS  Google Scholar 

  30. Juška, G. et al. Extraction of photogenerated charge carriers by linearly increasing voltage in the case of Langevin recombination. Phys. Rev. B 84, 155202 (2011).

    Article  ADS  Google Scholar 

  31. Nekrašas, N. et al. Features of current transients of photogenerated charge carriers, extracted by linearly increased voltage. Chem. Phys. 404, 56–59. (2012).

    Article  Google Scholar 

  32. Garcia-Belmonte, G. et al. Charge carrier mobility and lifetime of organic bulk heterojunctions analyzed by impedance spectroscopy. Org. Electron. 9, 847–851 (2008).

    Article  Google Scholar 

  33. Lilliu, S., Alsari, M., Bikondoa, O., Macdonald, J. E. & Dahlem, M. S. Absence of structural impact of noble nanoparticles on P3HT: PCBM blends for plasmon enhanced bulk-heterojunction organic solar cells probed by synchrotron GI-XRD. Sci. Rep. 5, 10633 (2015).

    Article  ADS  Google Scholar 

  34. Lilliu, S. et al. The influence of substrate and top electrode on the crystallization dynamics of P3HT:PCBM blends. Energy Proc. 31, 60–68 (2012).

    Article  Google Scholar 

  35. Lilliu, S. et al. Dynamics of crystallization and disorder during annealing of P3HT/PCBM bulk heterojunctions. Macromolecules 44, 2725–2734 (2011).

    Article  ADS  Google Scholar 

  36. Lilliu, S. et al. Effects of thermal annealing upon the nanomorphology of poly (3-hexylselenophene)-PCBM blends. Macromol. Rapid Comm. 32, 1454–1460 (2011).

    Article  Google Scholar 

  37. Huang, J. et al. Gd2O2S:Eu3+ and Gd2O2S:Eu3+/Gd2O2S hollow microspheres: Solvothermal preparation and luminescence properties. J.Alloy. Compd. 532, 34–40 (2012).

    Article  Google Scholar 

  38. Onoda, M., Chen, X.-a., Sato, A. & Wada, H. Crystal structure of Cu2Gd2/3S2: interlayer short-range order of Gd vacancies. J. Solid State Chem. 152, 332–339 (2000).

    Article  ADS  Google Scholar 

  39. Eick, H. A. The preparation, lattice parameters and some chemical properties of the rare earth mono-thio oxides. J. Am. Chem. Soc. 80, 43–44 (1958).

    Article  Google Scholar 

  40. Verploegen, E. et al. Effects of thermal annealing upon the morphology of polymer–fullerene blends. Adv. Funct. Mater. 20, 3519–3529 (2010).

    Article  Google Scholar 

  41. Pingree, L. S. C., Reid, O. G. & Ginger, D. S. Imaging the evolution of nanoscale photocurrent collection and transport networks during annealing of polythiophene/fullerene solar cells. Nano Lett. 9, 2946–2952 (2009).

    Article  ADS  Google Scholar 

  42. González, D. M. et al. Improved power conversion efficiency of P3HT: PCBM organic solar cells by strong spin–orbit coupling-induced delayed fluorescence. Adv. Eng. Mater. http://dx.doi.org/10.1002/aenm.201401770 (2015).

Download references

Acknowledgements

We thank the German Federal Ministry for Education and Research (BMBF) for funding this work (13N12377). P.B. is recipient of an Ernst von Siemens Doctoral Fellowship (Ernst-von-Siemens-Promotionsstipendium). Siemens Healthcare GmbH group thanks S. Szyszkowski and J. Hürdler for their enduring support. C.J.B. acknowledges funding by the Bavarian Ministry of Economic Affairs and Media, Energy and Technology for the Joint Projects of the Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy Production (HI ERN). M.R. thanks the German Research Foundation (DFG) for financial support through the Graduate School GRK 1896. We thank B. Curzadd for contributing with the design of a new GIWAXS chamber and for fabricating the chamber itself. We thank the XMaS beamline team for the support at the beamline, and M. S. Dahlem and M. Alsari for the help with the measurements at the beamline. G.N.A. and T.K. thank E. Arzt for his continuing support of the project.

Author information

Authors and Affiliations

  1. Siemens Healthcare GmbH, Technology Center, Erlangen, 91058, Germany

    Patric Büchele, Sandro F. Tedde, Rene Fischer, Markus Biele, Wilhelm Metzger & Oliver Schmidt

  2. Light Technology Institute and Institute of Microstructure Technology, Karlsruhe Institute of Technology, Karlsruhe, 76131, Germany

    Patric Büchele & Uli Lemmer

  3. Institute of Materials for Electronics and Energy Technology (i-MEET), Friedrich-Alexander-University Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany

    Moses Richter, Gebhard J. Matt, Rene Fischer, Markus Biele & Christoph J. Brabec

  4. INM – Leibniz Institute for New Materials, Campus D2 2, Saarbruecken, 66123, Germany

    Genesis N. Ankah & Tobias Kraus

  5. Masdar Institute of Science and Technology, Abu Dhabi, 54224, UAE

    Samuele Lilliu

  6. XMaS, The UK-CRG Beamline, ESRF-The European Synchrotron, CS40220, Grenoble Cedex 9, 38043, France

    Oier Bikondoa

  7. Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK

    Oier Bikondoa

  8. School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA, UK

    J. Emyr Macdonald

Authors
  1. Patric Büchele
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Moses Richter
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Sandro F. Tedde
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Gebhard J. Matt
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Genesis N. Ankah
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Rene Fischer
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Markus Biele
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Wilhelm Metzger
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Samuele Lilliu
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Oier Bikondoa
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. J. Emyr Macdonald
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Christoph J. Brabec
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Tobias Kraus
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. Uli Lemmer
    View author publications

    You can also search for this author in PubMed Google Scholar

  15. Oliver Schmidt
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

P.B. carried out device fabrication and characterization, and analysis of the results. M.R. executed X-CELIV experiments. G.N.A. executed FIB-cutting and SEM experiments. S.F.T. executed X-ray imaging and XRD measurements, as well as X-ray device analysis. R.F. executed X-ray imaging and arranged X-ray setup. M.B. executed and helped with analysis of pulse measurements. W.M. executed GOS:Tb characterization. G.J.M. conducted and helped with the X-CELIV measurement. S.L. directed, executed and analysed XRD experiments. O.B. set up the synchrotron beamline. J.E.M. submitted the proposal for XRD experiments and helped with the XRD analysis. C.J.B. directed and helped with X-CELIV analysis. T.K. directed and helped with FIB/SEM analysis. U.L. helped with optoelectronical characterization and analysis of X-ray response measurements. O.S. directed device fabrication, and helped with device analysis.

Corresponding authors

Correspondence to Patric Büchele or Oliver Schmidt.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 1536 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Büchele, P., Richter, M., Tedde, S. et al. X-ray imaging with scintillator-sensitized hybrid organic photodetectors. Nature Photon 9, 843–848 (2015). https://doi.org/10.1038/nphoton.2015.216

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nphoton.2015.216

This article is cited by

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