CdHgTe and CdTe quantum dot solar cells displaying an energy conversion efficiency exceeding 2%

We have fabricated quantum dot solar cells (QDSSCs) incorporating CdHgTe nanocrystals (NCs) and CdTe quantum dots (QDs), which we prepared separately from aqueous mixtures of NaHTe, Cd(NO3)(2), and 3-mercaptopropionic acid in the presence and absence of HgCl2, respectively. After depositing the CdHgTe NCs and CdTe QDs onto TiO2 electrodes coated with poly(dimethyldiallylammonium chloride), stabilized through electrostatic interactions, we obtained (CdHgTe)(3) and (CdHgTe)(3)-(CdTe)(2) QDSSCs having energy conversion efficiencies of 1.0% and 2.2%, respectively. The incident photon-to-current conversion efficiencies (IPCEs) of the (CdHgTe)(3) and (CdHgTe)(3)-(CdTe)(2) QDSSCs were 12.2% and 17.5%, respectively. The higher energy conversion efficiency of the (CdHgTe)(3)-(CdTe)(2) QDSSCs relative to that of the (CdTe)(3)-(CdHgTe)(2) QDSSCs resulted from the greater electron transfer efficiency in the former system. The combination of CdHgTe NCs and CdTe QDs and their deposition sequence are two important factors affecting the QDSSCs' efficiencies, which were controlled by their photocurrent densities and fill factors. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.