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Ultrasensitive solution-cast quantum dot photodetectors


Solution-processed electronic1 and optoelectronic2,3,4,5 devices offer low cost, large device area, physical flexibility and convenient materials integration compared to conventional epitaxially grown, lattice-matched, crystalline semiconductor devices. Although the electronic or optoelectronic performance of these solution-processed devices is typically inferior to that of those fabricated by conventional routes, this can be tolerated for some applications in view of the other benefits. Here we report the fabrication of solution-processed infrared photodetectors that are superior in their normalized detectivity (D*, the figure of merit for detector sensitivity) to the best epitaxially grown devices operating at room temperature. We produced the devices in a single solution-processing step, overcoating a prefabricated planar electrode array with an unpatterned layer of PbS colloidal quantum dot nanocrystals. The devices showed large photoconductive gains with responsivities greater than 103 A W-1. The best devices exhibited a normalized detectivity D* of 1.8 × 1013 jones (1 jones = 1 cm Hz1/2 W-1) at 1.3 µm at room temperature: today's highest performance infrared photodetectors are photovoltaic devices made from epitaxially grown InGaAs that exhibit peak D* in the 1012 jones range at room temperature, whereas the previous record for D* from a photoconductive detector lies at 1011 jones. The tailored selection of absorption onset energy through the quantum size effect, combined with deliberate engineering of the sequence of nanoparticle fusing and surface trap functionalization, underlie the superior performance achieved in this readily fabricated family of devices.

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Figure 1: Device structure and electro-optic characteristics for device classes investigated.
Figure 2: Noise characteristics and resultant normalized detectivity of the different device classes investigated.
Figure 3: Photodetector performance characteristics of the highest-sensitivity class of devices.


  1. Talapin, D. & Murray, C. B. PbSe nanocrystal solids for n- and p-channel thin film field-effect transistors. Science 310, 86–89 (2005)

    ADS  CAS  Article  Google Scholar 

  2. Tessler, N., Medvedev, V., Kazes, M., Kan, S. & Banin, U. Efficient near-infrared polymer nanocrystal light-emitting diodes. Science 295, 1506–1508 (2002)

    ADS  Article  Google Scholar 

  3. Konstantatos, G., Huang, C., Levina, L., Lu, Z. & Sargent, E. H. Efficient infrared electroluminescent devices using solution-processed colloidal quantum dots. Adv. Funct. Mater. 15, 1865–1869 (2005)

    CAS  Article  Google Scholar 

  4. Hoogland, S. et al. A solution-processed 1.53 µm quantum dot laser with temperature-invariant emission wavelength. Opt. Express 14, 3273–3281 (2006)

    ADS  CAS  Article  Google Scholar 

  5. McDonald, S. A. et al. Solution-processed PbS quantum dot infrared photodetectors and photovoltaics. Nature Mater. 4, 138–142 (2005)

    ADS  CAS  Article  Google Scholar 

  6. Schödel, R. et al. A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way. Nature 419, 694–696 (2002)

    ADS  Article  Google Scholar 

  7. Rawlings, S. et al. A radio galaxy at redshift 4.41. Nature 383, 502–505 (1996)

    ADS  CAS  Article  Google Scholar 

  8. Ettl, R., Chao, I., Diederich, F. & Whetten, R. L. Isolation of C76, a chiral (D2) allotrope of carbon. Nature 353, 149–153 (1991)

    ADS  CAS  Article  Google Scholar 

  9. Walker, J. Tunable alkali halide lasers. Nature 256, 695 (1975)

    ADS  Article  Google Scholar 

  10. Ettenberg, M. A little night vision. Adv. Imaging 20, 29–32 (2005)

    Google Scholar 

  11. Sargent, E. H. Infrared quantum dots. Adv. Mater. 17, 515–522 (2005)

    CAS  Article  Google Scholar 

  12. Lim1, Y. T. et al. Selection of quantum dot wavelengths for biomedical assays and imaging. Mol. Imaging 2, 50–64 (2003)

    CAS  Article  Google Scholar 

  13. Kim, S. et al. Near-infrared fluorescent type II quantum dots for sentinel lymph node mapping. Nature Biotechnol. 22, 93–97 (2004)

    CAS  Article  Google Scholar 

  14. Petritz, R. L. Theory of photoconductivity in semiconductor films. Phys. Rev. B 104, 1508–1516 (1956)

    ADS  CAS  Article  Google Scholar 

  15. Carbone, A. & Mazzetti, P. Grain-boundary effects on photocurrent fluctuations in polycrystalline photoconductors. Phys. Rev. B 57, 2454–2460 (1998)

    ADS  CAS  Article  Google Scholar 

  16. Murray, C. B., Norris, D. J. & Bawendi, M. G. Synthesis and characterization of nearly monodisperse CdE (E = sulfur, selenium, tellurium) semiconductor nanocrystallites. J. Am. Chem. Soc. 115, 8706–8715 (1993)

    CAS  Article  Google Scholar 

  17. Yu, D., Wang, C. & Guyot-Sionnest, P. n-Type conducting CdSe nanocrystal solids. Science 300, 1277–1280 (2003)

    ADS  CAS  Article  Google Scholar 

  18. Wessels, J. M. et al. Optical and electrical properties of three-dimensional interlinked gold nanoparticle assemblies. J. Am. Chem. Soc. 126, 3349–3356 (2004)

    CAS  Article  Google Scholar 

  19. Leatherdale, C. A. et al. Photoconductivity in CdSe quantum dot solids. Phys. Rev. B 62, 2669–2680 (2000)

    ADS  CAS  Article  Google Scholar 

  20. Jarosz, M. V., Porter, V. J., Fisher, B. R., Kastner, M. A. & Bawendi, M. G. Photoconductivity of treated CdSe quantum dot films exhibiting increased exciton ionization efficiency. Phys. Rev. B 70, 195327 (2004)

    ADS  Article  Google Scholar 

  21. Oertel, D. C., Bawendi, M. G., Arango, A. C. & Bulovic, V. Photodetectors based on treated CdSe quantum-dot films. Appl. Phys. Lett. 87, 213505 (2005)

    ADS  Article  Google Scholar 

  22. Hines, M. A. & Scholes, G. D. Colloidal PbS nanocrystals with size-tunable near-infrared emission: observation of post-synthesis self-narrowing of the particle size distribution. Adv. Mater. 15, 1844–1849 (2003)

    CAS  Article  Google Scholar 

  23. Yu, D., Wang, C., Wehrenberg, B. L. & Guyot-Sionnest, P. Variable range hopping mechanism in semiconductor nanocrystal solids. Phys. Rev. Lett. 92, 216802 (2004)

    ADS  Article  Google Scholar 

  24. Rahada, R. H. & Minden, H. T. Photosensitization of PbS films. Phys. Rev. 102, 1258–1262 (1956)

    ADS  Article  Google Scholar 

  25. Scher, H. Anomalous transit-time dispersion in amorphous solids. Phys. Rev. B 12, 2455–2477 (1975)

    ADS  CAS  Article  Google Scholar 

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We thank D. Grozea and Z. H. Lu for XPS, E. Istrate for discussions, and V. Sukhovatkin for assistance in optical measurements. This research was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Foundation for Innovation, the Province of Ontario, and the Canada Research Chairs programme.

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Correspondence to Edward H. Sargent.

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Konstantatos, G., Howard, I., Fischer, A. et al. Ultrasensitive solution-cast quantum dot photodetectors. Nature 442, 180–183 (2006).

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