Luminescent Colloidal InSb Quantum Dots from In Situ Generated Single-Source Precursor.

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Colloidal indium antimonide (InSb) quantum dot (QD) synthesis is challenging due to a lack of suitable precursors.
• Existing methods for InSb QD synthesis are underdeveloped, limiting their applications.

Purpose of the Study:

• To develop novel precursors for the synthesis of colloidal InSb quantum dots.
• To investigate the formation mechanism, crystal structure, and optical properties of the synthesized InSb QDs.
• To establish a correlation between the size of InSb QDs and their band gap energy.

Main Methods:

• In situ formation of InSb adduct complexes using Lewis acid-base interactions between indium(III) and antimony(III) species.
• Synthesis of colloidal InSb QDs via fast coreduction of the adduct complexes at high temperatures (≥230 °C).
• Post-synthetic size fractionation to obtain subensembles with narrow size distributions.

Main Results:

• Successfully synthesized InSb QDs with diameters ranging from 2.8 to 18.2 nm.
• Proposed a formation mechanism involving nonclassical nucleation and aggregative growth, leading to multimodal size distributions.
• Observed zinc blende crystal structure for QDs <7.0 nm and a mixture of wurtzite and zinc blende for larger QDs (≥10 nm).
• Demonstrated photoluminescence with small Stokes shifts and short radiative lifetimes, indicating band-edge recombination.
• Established a sizing curve showing a 1/d dependence of the band gap on QD diameter.

Conclusions:

• Novel InSb adduct complexes serve as effective precursors for colloidal InSb QD synthesis.
• The synthesis method allows for control over QD size and crystal structure.
• InSb QDs preserve the direct bandgap nature of bulk InSb, with tunable band gap energy via size control.