Size-Dependent Response of CdSe Quantum Dots to Hydrostatic Pressure

The size-dependent pressure response of oleatestabilized CdSe quantum dots (QDs) in paraffin is investigated using diamond anvil cell experiments and density functional theory (DFT). For QDs above 3.0 nm, the photoluminescence shows a blue-shift of around 43 meV/GPa, close to the value for bulk CdSe, but the shift increases strongly for nanocrystals less than 3 nm in size. Conversely, the absorption shift is 45 meV/GPa above 3.0 nm but weakens to 35 meV/GPa for particles 1.5 nm in size. No crystallographic phase transitions occur below 2 GPa, and the optical effects are reversible. DFT calculations confirm that shifts in the bulk modulus begin for sizes estimated to be 1/2 of the Bohr radius, which we term the extreme confinement regime.

Automated summary

The size-dependent pressure response of oleate-stabilized CdSe quantum dots in paraffin was investigated using diamond anvil cell experiments and density functional theory (DFT). The photoluminescence shows a blue-shift of around 43 meV/GPa for QDs above 3.0 nm, but the shift increases strongly for nanocrystals less than 3 nm in size. Conversely, the absorption shift is 45 meV/GPa above 3.0 nm but weakens to 35 meV/GPa for particles 1.5 nm in size. No crystallographic phase transitions occur below 2 GPa, and the optical effects are reversible. DFT calculations confirm that shifts in the bulk modulus begin for sizes estimated to be 1/2 of the Bohr radius, which we term the extreme confinement regime.