Synthesis and Characterization of Semiconductor Nanocrystals

Semiconductor nanocrystals, often termed quantum dots, are inorganic particles with dimensions typically below 10 nm. Their size-dependent optical and electronic properties arise from quantum confinement, making precise control of shape, composition and surface chemistry essential. Colloidal synthesis methods dominate the field, employing heat-up or hot-injection strategies to separate nucleation and growth. Precursor chemistry governs monomer supply, while ligands stabilise nascent nuclei and direct morphology. Recent advances have revealed multistep nucleation pathways, including the role of magic-size clusters as discrete intermediates. Characterization relies on a suite of techniques: transmission electron microscopy (TEM) for morphology, X-ray diffraction (XRD) and pair distribution function (PDF) analysis for crystal structure, small-angle X-ray scattering (SAXS) for size distributions, and optical spectroscopy for absorption and emission features. Together, these tools elucidate growth kinetics, surface-reaction mechanisms and structural transformations, guiding the rational design of nanocrystals for applications in lighting, displays, photovoltaics and bioimaging.

Research from Nature Portfolio

Controllable modulation of precursor reactivity using chemical additives has enabled systematic synthesis of high-quality quantum dots. By incorporating a boron–sulfur bond into a single sulphur precursor, its reactivity can be tuned in situ with commercially available Lewis bases. This approach unifies optimisation of temperature and precursor reactivity, yielding monodisperse nanocrystals with tailored size and crystallinity across multiple material systems. The methodology offers a general route to high-performance quantum dots without synthesising extensive precursor libraries.

An aqueous-phase, room-temperature method for CdS magic-size clusters has been developed, using primary amines to trigger thiourea decomposition in water. The resulting clusters exhibit sharp optical absorption and evolve via a pathway analogous to organic-phase syntheses. Insights into aggregation and ligand interactions have advanced mechanistic understanding of low-temperature cluster formation, opening routes to environmentally benign nanocrystal production.

Synthesis and Characterization of Semiconductor Nanocrystals publication trend

The graph below shows the total number of articles in synthesis and characterization of semiconductor nanocrystals across all publications each year (not limited to Nature Index journals).

Technical terms

Quantum dot: A semiconductor nanocrystal exhibiting size-dependent electronic and optical properties due to quantum confinement.

Magic-size cluster: A stable, atomically precise nanocluster that acts as an intermediate in colloidal nanocrystal growth.

Nucleation: The initial formation of an ordered crystalline nucleus from monomer species in solution.

Ligand: An organic molecule that binds to nanocrystal surfaces, controlling growth kinetics and stabilising colloids.

Pair distribution function (PDF): A technique analysing interatomic distances to determine local structure in nanocrystals.

Small-angle X-ray scattering (SAXS): A method to measure size, shape and assembly of particles in suspension at the nanoscale.

References

1. Controllable modulation of precursor reactivity using chemical additives for systematic synthesis of high-quality quantum dots. Nature Communications (2020).
2. Room-temperature formation of CdS magic-size clusters in aqueous solutions assisted by primary amines. Nature Communications (2020).
3. An Amorphous Phase Precedes Crystallization: Unraveling the Colloidal Synthesis of Zirconium Oxide Nanocrystals. ACS Nano (2023).
4. Direct Observation of Off‐Stoichiometry‐Induced Phase Transformation of 2D CdSe Quantum Nanosheets. Advanced Science (2023).
5. Stable CsPbBr3 Nanoclusters Feature a Disk-like Shape and a Distorted Orthorhombic Structure. Journal of the American Chemical Society (2022).