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.

  • Letter
  • Published:

Solar-energy conversion and light emission in an atomic monolayer p–n diode


The limitations of the bulk semiconductors currently used in electronic devices—rigidity, heavy weight and high costs—have recently shifted the research efforts to two-dimensional atomic crystals1 such as graphene2 and atomically thin transition-metal dichalcogenides3,4. These materials have the potential to be produced at low cost and in large areas, while maintaining high material quality. These properties, as well as their flexibility, make two-dimensional atomic crystals attractive for applications such as solar cells or display panels. The basic building blocks of optoelectronic devices are p–n junction diodes, but they have not yet been demonstrated in a two-dimensional material. Here, we report a p–n junction diode based on an electrostatically doped5 tungsten diselenide (WSe2) monolayer. We present applications as a photovoltaic solar cell, a photodiode and a light-emitting diode, and obtain light–power conversion and electroluminescence efficiencies of 0.5% and 0.1%, respectively. Given recent advances in the large-scale production of two-dimensional crystals6,7, we expect them to profoundly impact future developments in solar, lighting and display technologies.

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: WSe2 monolayer device with split gate electrodes.
Figure 2: Electrical characterization.
Figure 3: Device operation as solar cell and photodiode.
Figure 4: Device operation as light-emitting diode.

Similar content being viewed by others


  1. Novoselov, K. S. et al. Two-dimensional atomic crystals. Proc. Natl Acad. Sci. USA 102, 10451–10453 (2005).

    Article  CAS  Google Scholar 

  2. Novoselov, K. S. et al. Electric field effect in atomically thin carbon films. Science 306, 666–669 (2004).

    Article  CAS  Google Scholar 

  3. Radisavljevic, B., Radenovic, A., Brivio, J., Giacometti, V. & Kis, A. Single-layer MoS2 transistors. Nature Nanotech. 6, 147–150 (2011).

    Article  CAS  Google Scholar 

  4. Wang, Q. H., Kalantar-Zadeh, K., Kis, A., Coleman, J. N. & Strano, M. S. Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. Nature Nanotech. 7, 699–712 (2012).

    Article  CAS  Google Scholar 

  5. Gabor, N. M., Zhong, Z., Bosnick, K., Park, J. & McEuen, P. L. Extremely efficient multiple electron–hole pair generation in carbon nanotube photodiodes. Science 325, 1367–1371 (2009).

    Article  CAS  Google Scholar 

  6. Bae, S. et al. Roll-to-roll production of 30-inch graphene films for transparent electrodes. Nature Nanotech. 5, 574–578 (2010).

    Article  CAS  Google Scholar 

  7. Liu, K-K. et al. Growth of large-area and highly crystalline MoS2 thin layers on insulating substrates. Nano Lett. 12, 1538–1544 (2013).

    Article  Google Scholar 

  8. Stander, N., Huard, B. & Goldhaber-Gordon, D. Evidence for Klein tunneling in graphene p–n junctions. Phys. Rev. Lett. 102, 026807 (2009).

    Article  CAS  Google Scholar 

  9. Pospischil, A. et al. CMOS-compatible graphene photodetector covering all optical communication bands. Nature Photon. 7, 892–896 (2013).

    Article  CAS  Google Scholar 

  10. Wang, X., Zhi, L. & Müllen, K. Transparent, conductive graphene electrodes for dye-sensitized solar cells. Nano Lett. 8, 323–327 (2008).

    Article  CAS  Google Scholar 

  11. Han, T-H. et al. Extremely efficient flexible organic light-emitting diodes with modified graphene anode. Nature Photon. 6, 105–110 (2012).

    Article  CAS  Google Scholar 

  12. Britnell, L. et al. Strong light–matter interactions in heterostructures of atomically thin films. Sci. Express 340, 1311–1314 (2013).

    CAS  Google Scholar 

  13. Podzorov, V., Gershenson, M. E., Kloc, Ch., Zeis, R. & Bucher, E. High-mobility field-effect transistors based on transition metal dichalcogenides. Appl. Phys. Lett. 84, 3301–3303 (2004).

    Article  CAS  Google Scholar 

  14. Fang, H. et al. High-performance single layered WSe2 p-FETs with chemically doped contacts. Nano Lett. 12, 3788–3792 (2012).

    Article  CAS  Google Scholar 

  15. Liu, W. et al. Role of metal contacts in designing high-performance monolayer n-type WSe2 field effect transistors. Nano Lett. 13, 1983–1990 (2013).

    Article  CAS  Google Scholar 

  16. Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 115409 (2009).

    Google Scholar 

  17. Splendiani, A. et al. Emerging photoluminescence in monolayer MoS2 . Nano Lett. 10, 1271–1275 (2010).

    Article  CAS  Google Scholar 

  18. Zhang, Y. J., Ye, J. T., Yomogida, Y., Takenobu, T. & Iwasa, Y. Formation of a stable p–n junction in a liquid-gated MoS2 ambipolar transistor. Nano Lett. 13, 3023–3028 (2013).

    Article  CAS  Google Scholar 

  19. Tonndorf, P. et al. Photoluminescence emission and Raman response of monolayer MoS2, MoSe2, and WSe2 . Opt. Express 21, 4908–4916 (2013).

    Article  CAS  Google Scholar 

  20. Das, S., Chen, H-Y., Penumatcha, A. V. & Appenzeller, J. High performance multilayer MoS2 transistors with scandium contacts. Nano Lett. 13, 100–105 (2013).

    Article  CAS  Google Scholar 

  21. Zhang, Y., Ye, J., Matsuhashi, Y. & Iwasa, Y. Polymer ambipolar MoS2 thin flake transistors. Nano Lett. 13, 1983–1990 (2013).

    Article  Google Scholar 

  22. Radosavljević, M., Freitag, M., Thadani, K. V. & Johnson, A. T. Nonvolatile molecular memory elements based on ambipolar nanotube field effect transistors. Nano Lett. 2, 761–764 (2002).

    Article  Google Scholar 

  23. Kim, W. et al. Hysteresis caused by water molecules in carbon nanotube field-effect transistors. Nano Lett. 3, 193–198 (2003).

    Article  CAS  Google Scholar 

  24. Das, S. & Appenzeller, J. WSe2 field effect transistors with enhanced ambipolar characteristics. Appl. Phys. Lett. 103, 103501 (2013).

    Article  Google Scholar 

  25. Fontana, M. et al. Electron–hole transport and photovoltaic effect in gated MoS2 Schottky junctions. Sci. Rep. 3, 1634 (2013).

    Article  Google Scholar 

  26. Späh, R., Elrod, U., LuxSteiner, M., Bucher, E. & Wagner, S. pn junctions in tungsten diselenide. Appl. Phys. Lett. 43, 79–81 (1983).

    Article  Google Scholar 

  27. Sundaram, R. S. et al. Electroluminescence in single layer MoS2 . Nano Lett. 13, 1416–1421 (2013).

    Article  CAS  Google Scholar 

  28. Chen, J. et al. Bright infrared emission from electrically induced excitons in carbon nanotubes. Science 310, 1171–1174 (2005).

    Article  CAS  Google Scholar 

  29. Ross, J. S. et al. Electrical control of neutral and charged excitons in a monolayer semiconductor. Nature Commun. 4, 1474 (2013).

    Article  Google Scholar 

  30. Mak, K. F. et al. Tightly bound trions in monolayer MoS2 . Nature Mater. 12, 207–211 (2013).

    Article  CAS  Google Scholar 

  31. Gong, Z. et al. Magnetoelectric effects and valley controlled spin quantum gates in transition metal dichalcogenide bilayers. Nature Commun. 4, 2053 (2013).

    Article  Google Scholar 

  32. Baugher, B. W. H., Churchill, H. O. H., Yafang, Y. & Jarillo-Herrero, P. Optoelectronic devices based on electrically tunable p–n diodes in a monolayer dichalcogenide. Nature Nanotech. (2014).

  33. Ross, J. S. et al. Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 p–n junctions. Nature Nanotech. (2014).

Download references


The authors thank K. Unterrainer for encouragement, M. Brandstetter, M. Krall and W. Schrenk for technical assistance and E. Bertagnolli for providing access to a Raman spectrometer. The research leading to these results has received funding from the Austrian Science Fund FWF (START Y-539) and the European Union Seventh Framework Programme (grant agreement no. 604391 Graphene Flagship).

Author information

Authors and Affiliations



T.M. conceived the experiment. A.P. fabricated the devices and carried out the measurements. M.F. contributed to sample fabrication. A.P. and M.F. built the experimental set-ups. A.P. and T.M. analysed the data. T.M. prepared the manuscript. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Thomas Mueller.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 744 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Pospischil, A., Furchi, M. & Mueller, T. Solar-energy conversion and light emission in an atomic monolayer p–n diode. Nature Nanotech 9, 257–261 (2014).

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