Tuning the energy bandgap of CdSe nanocrystals via Mg doping

Abstract

CdSe nanocrystals with a zinc blende structure allowed apparent Mg doping (∼9.8 at.%). Inverse micelles were formed at a low temperature as templates for the zinc blende CdSe nanocrystals, and paraffin oil and oleic acid were used as a solvent and a surfactant, respectively. The Mg doping was shown by energy dispersive x-ray spectroscopy (EDS) and inductively coupled plasma (ICP) atomic emission analyses. Although the particle size of the CdSe and Mg-doped CdSe nanocrystals were ∼6 and ∼8 nm, respectively, the Mg-doped ones show the obvious blueshift in the UV–visible absorption spectra due to the increase in the bulk energy bandgap, which is decisive evidence for the real Mg doping in the CdSe lattices. The Mg-doped CdSe nanocrystals also showed the blueshift in the photoluminescence (PL) spectra, and their PL intensity was comparable to or even higher than that of the undoped CdSe. This impurity doping using the zinc blende structure is suggested as a simple and effective way to tune the energy bandgap of CdSe nanocrystals and, in turn, to control their light emission colour.

CdSe/ZnS-doped silicophosphate films prepared by sol–gel method

“…According to [29], the energy band gap dependency on the size of semiconductor QDs is approximated using the Eq. (1):…”

Composition-controlled optical properties of colloidal CdSe quantum dots

“…with size tunability to obtain desired optoelectronic properties [8][9][10][11][12]. CdSe is one of the members in this group, with an intrinsic direct band gap of 1.74 eV [13] that can be tuned across the visible spectrum, thus making it an interesting material for various applications, such as light-emitting diodes (LEDs) [14][15][16][17], solar cells [18][19][20], biological labeling [21][22][23], etc.…”

Controlled Synthesis of CdSe Quantum Dots by a Microwave‐Enhanced Process: A Green Approach for Mass Production

“…[32] The size dependence of the average lifetime indicates that there is an optimum surface construction or surface morphology during the growth of nanocrystals. [37] As a result, the average lifetime t av increases slightly with increasing reaction time and temperature as a result of an increase in the particle size.…”

“…[35][36][37] The particle sizes of CdSe QDs as estimated by UV, XRD, and TEM are presented in Table 2.…”

“…[48] Because the QDs are perfectly crystallized, as shown in Figures 4 and 5, the localized states are mainly on the QD surfaces. [37] It has been suggested that the energy levels of the radiative surface traps at CdSe QDs are near the band edge. [49] The presence of a recombination channel via nonradiative surface traps will lead to a decrease in PL QY.…”