Composition tuning of rectifying polarity of colloidal CdS1−x Se x nanocrystal-based devices

Abstract

CdS1–xSex colloidal nanocrystals (NCs) were synthesized by colloidal chemistry route. Both lattice parameters and band structure were modulated by tuning the content of Se. As the Se content increases, the peak of UV–Visible absorbance spectrum of CdS1−xSex shifts toward longer wavelength direction, indicating the reduction of band gap. Devices with Au/CdS1−xSex NCs/Au structures have been fabricated by assembling the obtained CdS1−xSex NCs into Au microelectrodes via dielectrophoresis method. It is found that the rectifying polarities of the devices are strongly dependent on the content of Se. With the increasing Se content, the rectification polarity changes from backward to forward. This polarity tuning could be caused by the change of the relative height of the Fermi levels between CdS1−xSex and Au. The Se-content-dependent rectifying behavior may offer us an opportunity to design novel logical structure in NC-based nanoelectronics.