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Charge dynamics at heterojunctions for PbS/ZnO colloidal quantum dot solar cells probed with time-resolved surface photovoltage spectroscopy

Spencer, BF; Leontiadou, M; Clark, PCJ; Williamson, AI; Silly, MG; Sirotti, F; Fairclough, SM; Tsang, SCE; Neo, DCJ; Assender, HE; Watt, AAR; Flavell, WR

Charge dynamics at heterojunctions for PbS/ZnO colloidal quantum dot solar cells probed with time-resolved surface photovoltage spectroscopy Thumbnail


Authors

BF Spencer

PCJ Clark

AI Williamson

MG Silly

F Sirotti

SM Fairclough

SCE Tsang

DCJ Neo

HE Assender

AAR Watt

WR Flavell



Abstract

Time-resolved laser-pump X-ray-photoemission-probe spectroscopy of a ZnO (101 ⎯ ⎯ 0
101¯0
) substrate with and without PbS quantum dots (QDs) chemically linked to the surface is performed, using laser photon energies resonant with and below the band gap energy of the substrate (λ = 372 and 640 nm, hν = 3.33 and 1.94 eV). Charge injection from the photoexcited QDs to ZnO is demonstrated through the change in the surface photovoltage of the ZnO substrate observed when the heterojunction is illuminated with 1.94 eV radiation. The measured carrier dynamics are limited by the persistent photoconductivity of ZnO, giving dark carrier lifetimes of the order of 200 μs in a depletion layer at the interface. The chemical specificity of soft X-rays is used to separately measure the charge dynamics in the quantum dots and the substrate, yielding evidence that the depletion region at the interface extends into the PbS QD layer.

Citation

Spencer, B., Leontiadou, M., Clark, P., Williamson, A., Silly, M., Sirotti, F., …Flavell, W. (2016). Charge dynamics at heterojunctions for PbS/ZnO colloidal quantum dot solar cells probed with time-resolved surface photovoltage spectroscopy. Applied Physics Letters, 108(9), 091603. https://doi.org/10.1063/1.4943077

Journal Article Type Article
Acceptance Date Feb 18, 2016
Online Publication Date Mar 1, 2016
Publication Date Mar 1, 2016
Deposit Date Apr 1, 2019
Publicly Available Date Apr 1, 2019
Journal Applied Physics Letters
Print ISSN 0003-6951
Publisher AIP Publishing
Volume 108
Issue 9
Pages 091603
DOI https://doi.org/10.1063/1.4943077
Publisher URL https://doi.org/10.1063/1.4943077
Related Public URLs https://aip.scitation.org/journal/apl

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