TY - JOUR
T1 - Electrochemical modulation of the photophysics of surface-localized trap states in core/shell/(shell) quantum dot films
AU - Van Der Stam, Ward
AU - Grimaldi, Gianluca
AU - Geuchies, Jaco J.
AU - Gudjonsdottir, Solrun
AU - Van Uffelen, Pieter T.
AU - Van Overeem, Mandy
AU - Brynjarsson, Baldur
AU - Kirkwood, Nicholas
AU - Houtepen, Arjan J.
N1 - Funding Information:
A.J.H. acknowledges support from the European Research Council Horizon 2020 ERC Grant agreement no. 678004 (Doping on Demand). The authors acknowledge Anneke Kraamer and Hamit Eren for valuable discussions.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/10/22
Y1 - 2019/10/22
N2 - In this work, we systematically study the spectroelectrochemical response of CdSe quantum dots (QDs), CdSe/CdS core/shell QDs with varying CdS shell thicknesses, and CdSe/CdS/ZnS core/shell/shell QDs in order to elucidate the influence of localized surface trap states on the optoelectronic properties. By correlating the differential absorbance and the photoluminescence upon electrochemically raising the Fermi level, we reveal that trap states near the conduction band (CB) edge give rise to nonradiative recombination pathways regardless of the CdS shell thickness, evidenced by quenching of the photoluminescence before the CB edge is populated with electrons. This points in the direction of shallow trap states localized on the CdS shell surface that give rise to nonradiative recombination pathways. We suggest that these shallow trap states reduce the quantum yield because of enhanced hole trapping when the Fermi level is raised electrochemically. We show that these shallow trap states are removed when additional wide band gap ZnS shells are grown around the CdSe/CdS core/shell QDs.
AB - In this work, we systematically study the spectroelectrochemical response of CdSe quantum dots (QDs), CdSe/CdS core/shell QDs with varying CdS shell thicknesses, and CdSe/CdS/ZnS core/shell/shell QDs in order to elucidate the influence of localized surface trap states on the optoelectronic properties. By correlating the differential absorbance and the photoluminescence upon electrochemically raising the Fermi level, we reveal that trap states near the conduction band (CB) edge give rise to nonradiative recombination pathways regardless of the CdS shell thickness, evidenced by quenching of the photoluminescence before the CB edge is populated with electrons. This points in the direction of shallow trap states localized on the CdS shell surface that give rise to nonradiative recombination pathways. We suggest that these shallow trap states reduce the quantum yield because of enhanced hole trapping when the Fermi level is raised electrochemically. We show that these shallow trap states are removed when additional wide band gap ZnS shells are grown around the CdSe/CdS core/shell QDs.
UR - http://www.scopus.com/inward/record.url?scp=85073056706&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.9b02908
DO - 10.1021/acs.chemmater.9b02908
M3 - Article
AN - SCOPUS:85073056706
SN - 0897-4756
VL - 31
SP - 8484
EP - 8493
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 20
ER -