Charge Separation in Type II Tunneling Multilayered Structures of CdTe and CdSe Nanocrystals Directly Proven by Surface Photovoltage Spectroscopy

Charge separation and diffusion in type II multilayered structures of CdTe and CdSe nanocrystals with a polymer spacer are unambiguously proven by surface photovoltage spectroscopy. Holes accumulate in CdTe nanocrystal layers, and the electrons in CdSe nanocrystal layers. An increase of thickness of the polymer spacer strongly decreases the charge separation efficiency. Surface photovoltage transients demonstrate diffusion of the separated charges over several layers of the same kind of nanocrystals.