Abstract
This paper describes the pH dependence of the excitonic energies and dynamics of CdS quantum dots (QDs) capped with phosphonopropionate (PPA) in water. QDs capped with PPA carry a negative charge on their surfaces upon deprotonation of PPA above pH ∼ 8.5; the resultant electric field induces large changes in the QD's optical properties. Between pH 5.6 and 12.0, an increase in pH is accompanied by a 47-meV bathochromic shift in the bandgap of the QDs and a decrease in the Stokes shift by ∼4.3 meV/pH unit. An increase in the radiative recombination rate by a factor of 20.9 occurs on increasing the pH from 5.6 to 9.4. These observations are attributed to a shifting of the energy levels within the first exciton manifold, and are simulated using time-dependent density functional theory calculations on model Cd29S29 clusters surrounded by point charges.
| Original language | English |
|---|---|
| Pages (from-to) | 3954-3960 |
| Number of pages | 7 |
| Journal | Journal of Physical Chemistry Letters |
| Volume | 7 |
| Issue number | 19 |
| DOIs | |
| Publication status | Published - Oct 6 2016 |
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ASJC Scopus subject areas
- Materials Science(all)
Cite this
Electrostatic Control of Excitonic Energies and Dynamics in a CdS Quantum Dot through Reversible Protonation of Its Ligands. / Thompson, Christopher M.; Kodaimati, Mohamad; Westmoreland, Dana; Calzada, Raul; Weiss, Emily A.
In: Journal of Physical Chemistry Letters, Vol. 7, No. 19, 06.10.2016, p. 3954-3960.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Electrostatic Control of Excitonic Energies and Dynamics in a CdS Quantum Dot through Reversible Protonation of Its Ligands
AU - Thompson, Christopher M.
AU - Kodaimati, Mohamad
AU - Westmoreland, Dana
AU - Calzada, Raul
AU - Weiss, Emily A
PY - 2016/10/6
Y1 - 2016/10/6
N2 - This paper describes the pH dependence of the excitonic energies and dynamics of CdS quantum dots (QDs) capped with phosphonopropionate (PPA) in water. QDs capped with PPA carry a negative charge on their surfaces upon deprotonation of PPA above pH ∼ 8.5; the resultant electric field induces large changes in the QD's optical properties. Between pH 5.6 and 12.0, an increase in pH is accompanied by a 47-meV bathochromic shift in the bandgap of the QDs and a decrease in the Stokes shift by ∼4.3 meV/pH unit. An increase in the radiative recombination rate by a factor of 20.9 occurs on increasing the pH from 5.6 to 9.4. These observations are attributed to a shifting of the energy levels within the first exciton manifold, and are simulated using time-dependent density functional theory calculations on model Cd29S29 clusters surrounded by point charges.
AB - This paper describes the pH dependence of the excitonic energies and dynamics of CdS quantum dots (QDs) capped with phosphonopropionate (PPA) in water. QDs capped with PPA carry a negative charge on their surfaces upon deprotonation of PPA above pH ∼ 8.5; the resultant electric field induces large changes in the QD's optical properties. Between pH 5.6 and 12.0, an increase in pH is accompanied by a 47-meV bathochromic shift in the bandgap of the QDs and a decrease in the Stokes shift by ∼4.3 meV/pH unit. An increase in the radiative recombination rate by a factor of 20.9 occurs on increasing the pH from 5.6 to 9.4. These observations are attributed to a shifting of the energy levels within the first exciton manifold, and are simulated using time-dependent density functional theory calculations on model Cd29S29 clusters surrounded by point charges.
UR - http://www.scopus.com/inward/record.url?scp=84990019671&partnerID=8YFLogxK
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U2 - 10.1021/acs.jpclett.6b01899
DO - 10.1021/acs.jpclett.6b01899
M3 - Article
VL - 7
SP - 3954
EP - 3960
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
SN - 1948-7185
IS - 19
ER -