Tunable optical properties of colloidal quantum dots in electrolytic environments

Abstract

The absorption spectra of colloidal cadmium sulfide quantum dots in electrolytic solutions are found to manifest a shift in the absorption threshold as the concentration of the electrolyte is varied. These results are consistent with a shift in the absorption threshold that would be caused by electrolytic screening of the field caused by the intrinsic spontaneous polarisation of these würtzite structured quantum dots. These electrolyte-dependent absorption properties provide a potential means of gaining insights on the variable extracellular and intracellular electrolytic concentrations that are present in biological systems.

Sizing, stoichiometry and optical absorbance variations of colloidal cadmium sulphide nanoparticles

“…The idea that Q dots have a band gap influenced by features other than size (for example charge effects [52]) has been suggested. However, the work described herein shows that cadmium sulphide particles may possess non-'bulk-like' properties at much larger particle sizes.…”

Spontaneous polarization effects in nanoscale wurtzite structures

“…Wutzite-based nanostructures have attracted attention in applications ranging from nanoelectronics, to optoelectronics, to nanobiosensors [1][2][3][4][5][6]. The spontaneous polarization of selected wurtzite materials is known to lead to significant device-related effects including built-in electrostatic potentials of up to a few MV/cm [1].…”

“…In addition, the use of colloidal quantum dots with built-in polarizations has been considered in biological applications including the interaction of manmade nanostructures with ion channels in neurons [2][3][4]. Moreover, the band bending in such colloidal quantum dots has been investigated as a useful indicator of the electric field strength in the neighborhood of such a quantum dot [7].…”

Blinking mechanism of colloidal semiconductor quantum dots: Blinking mechanisms

“…The magnitudes of the charges on these nanocrystals generally fall within the range of 0 < n < 10 depending on the pH of the suspension and these charges are, of course, compensated by opposite charges in the electrolyte [11]. Using the PoissonBoltzmann equation [9,12] describing the electric potential near a charged interface [13], it follows that the surface charge density, σ , is given by,…”