TY - JOUR
T1 - Subpicosecond Photoinduced Hole Transfer from a CdS Quantum Dot to a Molecular Acceptor Bound Through an Exciton-Delocalizing Ligand
AU - Lian, Shichen
AU - Weinberg, David J.
AU - Harris, Rachel D.
AU - Kodaimati, Mohamad S.
AU - Weiss, Emily A.
N1 - Funding Information:
This material is based upon work supported by the National Science Foundation under CHE-1400596. S.L. would like to thank the Center for Bio-Inspired Energy Science (CBES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under award no. DE-SC0000989, for a graduate student fellowship. R.D.H. is supported by the National Science Foundation through a Graduate Research Fellowship (grant no. DGE-1324585).
PY - 2016/6/28
Y1 - 2016/6/28
N2 - This paper describes the enhancement of the rate of hole transfer from a photoexcited CdS quantum dot (QD), with radius R = 2.0 nm, to a molecular acceptor, phenothiazine (PTZ), by linking the donor and acceptor through a phenyldithiocarbamate (PTC) linker, which is known to lower the confinement energy of the excitonic hole. Upon adsorption of PTC, the bandgap of the QD decreases due to delocalization of the exciton, primarily the excitonic hole, into interfacial states of mixed QD/PTC character. This delocalization enables hole transfer from the QD to PTZ in <300 fs (within the instrument response of the laser system) when linked by PTC, but not when linked by a benzoate group, which has a similar length and conjugation as PTC but does not delocalize the excitonic hole. Comparison of the two systems was aided by quantification of the surface coverage of benzoate and PTC-linked PTZ by 1H NMR. This work provides direct spectroscopic evidence of the enhancement of the rate of hole extraction from a colloidal QD through covalent linkage of a hole acceptor through an exciton-delocalizing ligand.
AB - This paper describes the enhancement of the rate of hole transfer from a photoexcited CdS quantum dot (QD), with radius R = 2.0 nm, to a molecular acceptor, phenothiazine (PTZ), by linking the donor and acceptor through a phenyldithiocarbamate (PTC) linker, which is known to lower the confinement energy of the excitonic hole. Upon adsorption of PTC, the bandgap of the QD decreases due to delocalization of the exciton, primarily the excitonic hole, into interfacial states of mixed QD/PTC character. This delocalization enables hole transfer from the QD to PTZ in <300 fs (within the instrument response of the laser system) when linked by PTC, but not when linked by a benzoate group, which has a similar length and conjugation as PTC but does not delocalize the excitonic hole. Comparison of the two systems was aided by quantification of the surface coverage of benzoate and PTC-linked PTZ by 1H NMR. This work provides direct spectroscopic evidence of the enhancement of the rate of hole extraction from a colloidal QD through covalent linkage of a hole acceptor through an exciton-delocalizing ligand.
KW - CdS quantum dot
KW - dithiocarbamate
KW - electronic coupling
KW - exciton delocalization
KW - hole transfer
KW - transient absorption spectroscopy
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U2 - 10.1021/acsnano.6b02814
DO - 10.1021/acsnano.6b02814
M3 - Article
AN - SCOPUS:84976590819
VL - 10
SP - 6372
EP - 6382
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 6
ER -