Cluster-Seeded Synthesis of Doped CdSe:Cu₄ Quantum Dots

Abstract

We report here a method for synthesizing CdSe quantum dots (QDs) containing copper such that each QD is doped with four copper ions. The synthesis is a derivative of the cluster-seed method, whereby organometallic clusters act as nucleation centers for quantum dots. The method is tolerant of the chemical identity of the seed; as such, we have doped four copper ions into CdSe QDs using [Na(H2O)3]2[Cu4(SPh)6] as a cluster seed. The controlled doping allows us to monitor the photophysical properties of guest ions with X-ray spectroscopy, specifically XANES and EXAFS at the copper K-edge. These data reveal that copper can capture both electrons and holes from photoexcited CdSe QDs. When the dopant is oxidized, photoluminescence is quenched and the copper ions translocate within the CdSe matrix, which slows the return to an emissive state.

Ferromagnetic excited-state Mn2+dimers in Zn1−xMnxSe quantum dots observed by time-resolved magnetophotoluminescence

“…Although the materials investigated here are not immediately applicable for optical switching, the sensitized S = 0 → 4 photoexcitation within a semiconductor, combined with the 100% circularly polarized luminescence of this excited state under a magnetic field, is highly attractive for further investigation in this regard. For example, future synthetic advances may open routes to materials containing only dimers or related small clusters [67]. In such materials, these photoinduced spin-state changes would manifest themselves as giant Zeeman splittings of the semiconductor band structure in ways that could be useful for optically triggered spin filtering or spin transduction applications.…”

Near‐Unity Emitting Copper‐Doped Colloidal Semiconductor Quantum Wells for Luminescent Solar Concentrators

“…These are due to different oxidation states (Cu 1+ , Cu 2+ ) of copper reported for the doped-NC ground state. 3,5,6,[24][25][26][27] In the last few years, colloidal nanoplatelets (NPLs) have attracted great interest, which are also known as colloidal quantum wells (CQWs) due to their strong 1D confinement. 28,29 As compared to the CQDs, this new class of NCs have shown superior optical properties including narrow spontaneous emission spectra, suppressed inhomogeneous emission broadening, extremely large linear and nonlinear absorption cross-sections 30,31 and giant oscillator strengths.…”

14.1: Invited Paper: Heavy Metal‐Free Quantum Dots for Display Applications

“…Nanoco has developed a patented "molecular seeding" method of synthesis, 3 which avoids a high temperature nucleation step by using molecules of a cluster compound to act as nucleation sites for nanoparticle growth. 4 Growth is then sustained, until the desired particle size is reached, by the periodic addition of precursors at modest temperatures. The molecular seeding approach is versatile in that it can be used to synthesise binary, ternary, quaternary and alloyed QD systems, simply by choice of the elements contained within the seed used, elements within the precursors and the precursor ligand design.…”