Strategic PbS quantum dot-based multilayered photoanodes for high efficiency quantum dot-sensitized solar cells

Abstract

In2S3 is employed as a new passivation layer in PbS quantum dot-based multilayered photoanodes to coalesce the improvement in photocurrent density (J(SC)) and open-circuit voltage. Suppression of detrimental interfacial charge carrier recombination in In2S3/PbS/TiO2 and In2S3/PbS/CdS/TiO2 multilayered photoanodes, attributed to the In2S3 passivation layer, leads to increased V-OC in both photoanodes. In particular, In2S3/PbS/CdS/TiO2 multilayered photoanode exhibited a substantial improvement of similar to 36% (from 3.2 to 4.3%) in power conversion efficiency, which is attributed to significant increase in J(SC) value of similar to 26 mA/cm(2) by enhanced PbS loading and co-sensitizing effect of CdS along with substantially suppressed interfacial recombination. In-depth electrochemical impedance spectroscopic analysis revealed that the resistance against back-transfer of electrons to electrolyte can be subtly modulated by incorporating In2S3 deposition over PbS. Further, this multiple passivation layer turned out to be beneficial for improving photocorrosion of PbS in a polysulfide electrolyte. (C) 2016 Elsevier Ltd. All rights reserved.