Effect of Ligand Exchange on the Photoluminescence Properties of Cu-Doped Zn-In-Se Quantum Dots
Abstract
The surface-bound ligands of a semiconductor nanocrystal can affect its electron transition behavior. We investigate the photoluminescence (PL) properties of Cu-doped Zn-In-Se quantum dots (QDs) through the exchange of oleylamine with 6-mercaptohexanol (MCH). Fourier transform infrared and 1H nuclear magnetic resonance spectroscopies, and mass spectrometry reveal that the short-chain MCH molecules are bound to the QD surface. The emission peaks remain unchanged after ligand exchange, and the PL quantum yield is reduced from 49% to 38%. The effects of particle size and defect type on the change in PL behavior upon ligand substitution are excluded through high-resolution transmission electron microscopy, UV-Vis absorption, and PL spectroscopies. The origin of the decreased PL intensity is associated with increased ligand density and the stronger ligand electron-donating abilities of MCH-capped QDs that induce an increase in the nonradiative transition probability. A lower PL quenching transition temperature is observed for MCH-capped QDs and is associated with increasing electron-acoustic phonon coupling due to the lower melting temperature of MCH.
- Publication:
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Journal of Electronic Materials
- Pub Date:
- April 2018
- DOI:
- 10.1007/s11664-017-6050-3
- Bibcode:
- 2018JEMat..47.2241D
- Keywords:
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- Cu-doped Zn-In-Se quantum dots;
- photoluminescence;
- ligand density