Investigation of interfacial charge separation at PbS QDs/(001) TiO2 nanosheets heterojunction solar cell

Elham Ghadiri, Bin Liu, Jacques E. Moser, Michael Grätzel*, Lioz Etgar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

In the recent years, the heterojunction solar cells based on quantum dots (QDs) have attracted attention due to strong light absorbing characteristics and the size effect on the bandgap tuning. This paper reports on the kinetics of interfacial charge separation of PbS QDs/(001) TiO2 nanosheets heterojunction solar cells. PbS QDs are deposited using a bifunctional linker molecule on two different TiO2 films, i.e., TiO2 nanosheets (with 001 dominant exposed facet) and TiO2 nanoparticles (with 101 dominant exposed facet). Upon bandgap excitation, electrons are transferred from the PbS QDs conduction band to the lower lying conduction band of TiO2. Based on the ultrafast pump-probe laser spectroscopy technique, the kinetics of charge separation is scrutinized at the PbS/TiO2 interface. The interfacial charge separation at PbS/TiO2 nanosheets films made of (001) dominant exposed facets is five times faster than that on (101) dominant exposed facets TiO2 nanoparticles. The quantum yields for charge injection are higher for the (001) TiO2 nanosheets than the (101) TiO2 nanoparticles due to enhanced interfacial interaction with (001) surface compared to the (101) nanoparticles. The superior interfacial charge separation at PbS/(001) nanosheets respect to PbS/(101) nanoparticles is consistent with the higher photocurrent and enhanced power conversion efficiency in the PbS QDs/(001) TiO2 heterojunction solar cell. The use of (001) TiO2 nanosheets can be a better alternative to conventional mesoporous TiO2 films in QD heterojunction solar cells and perovskites-based heterojunction solar cells. The interfacial charge separation at TiO2 (001) nanosheets/PbS QDs interface is five times faster than that on standard TiO2 (101) nanoparticles. This observation is consistent with the enhanced power conversion efficiency in (001) TiO2/PbS QDs heterojunction solar cell.

Original languageAmerican English
Pages (from-to)483-488
Number of pages6
JournalParticle and Particle Systems Characterization
Volume32
Issue number4
DOIs
StatePublished - 1 Apr 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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