Mapping the energy band structure of nanocrystal monolayers under ambient conditions

With increasing demand for scale minimization of integrated circuit, nanostructures are likely to become primary components of future electronic devices. Self-assembled hybrid organic molecule-nanocrystal devices propose a prospective route for achieving this goal. In this type of devices, the characterization of the energy band structure of the semiconductor nanocrystal layers is of major importance. Recent works used scanning tunneling spectroscopy to measure locally the single nanocrystal band structure. These measurements are expensive, complicated, and usually done at low temperatures. In this work, we map the energy band structure of a monolayer using a simple hybrid device under ambient conditions. The ensemble band structure is similar to results achieved by scanning tunneling microscopy. In most cases, the energy band edges are wider due to the size distribution in consistence with photoluminescence results.