Optoelectronic devices based on electrically tunable p-n diodes in a monolayer dichalcogenide

Nat Nanotechnol. 2014 Apr;9(4):262-7. doi: 10.1038/nnano.2014.25. Epub 2014 Mar 9.


The p-n junction is the functional element of many electronic and optoelectronic devices, including diodes, bipolar transistors, photodetectors, light-emitting diodes and solar cells. In conventional p-n junctions, the adjacent p- and n-type regions of a semiconductor are formed by chemical doping. Ambipolar semiconductors, such as carbon nanotubes, nanowires and organic molecules, allow for p-n junctions to be configured and modified by electrostatic gating. This electrical control enables a single device to have multiple functionalities. Here, we report ambipolar monolayer WSe2 devices in which two local gates are used to define a p-n junction within the WSe2 sheet. With these electrically tunable p-n junctions, we demonstrate both p-n and n-p diodes with ideality factors better than 2. Under optical excitation, the diodes demonstrate a photodetection responsivity of 210 mA W(-1) and photovoltaic power generation with a peak external quantum efficiency of 0.2%, promising values for a nearly transparent monolayer material in a lateral device geometry. Finally, we demonstrate a light-emitting diode based on monolayer WSe2. These devices provide a building block for ultrathin, flexible and nearly transparent optoelectronic and electronic applications based on ambipolar dichalcogenide materials.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Nanotubes, Carbon*
  • Optics and Photonics / instrumentation*
  • Optics and Photonics / methods*
  • Semiconductors*
  • Solar Energy*
  • Tungsten Compounds


  • Nanotubes, Carbon
  • Tungsten Compounds