Colloidal Semiconductor Nanocrystals and Their Optical Applications

Colloidal semiconductor nanocrystals are nanometre-scale particles synthesised in solution, whose electronic and optical properties can be precisely tuned by size, composition and surface chemistry. Their discrete energy levels give rise to size-dependent photoluminescence spanning the visible and near-infrared spectra. Advances in synthetic control have enabled the development of core–shell heterostructures, graded alloys and doped architectures with enhanced quantum yields, suppressed non-radiative losses and tailored emission lifetimes. Such features underpin their utility in light-emitting diodes, displays, luminescent solar concentrators, photodetectors and bioimaging agents. Recent efforts have focused on cadmium-free systems—particularly I–III–VI ternary and quaternary compositions—to address environmental and health concerns without compromising performance. Surface passivation strategies, heteroepitaxial shell growth and stoichiometry control have elevated photoluminescence efficiencies to near-unity in visible emitters, while wide-bandgap materials and shell engineering have yielded deep-blue and near-infrared emission. Interdisciplinary research now converges on scalable synthesis, device integration and long-term stability, propelling colloidal nanocrystals towards commercial and biomedical applications worldwide.

Research from Nature Portfolio

Recent studies have demonstrated coherent heteroepitaxial growth of Ag(In,Ga)S₂ cores with AgGaS₂ shells, achieving near-unity photoluminescence quantum yields across almost the full visible spectrum (460–620 nm) while maintaining narrow emission linewidths and enhanced photochemical stability. The type I heterojunction formed by the coherent interface confines charge carriers within the emissive core, minimising interfacial defects and boosting absorption cross-sections. These robust nanocrystals have been successfully applied in luminescent solar concentrators and display technologies. Another key development is the microwave-assisted synthesis of Cd-free AgInS₂ and AgInS₂@ZnS quantum dots, stabilised with glutathione ligands, which exhibit tunable visible emission (500–600 nm), improved quantum yields and long lifetimes. Their water solubility and benign composition have enabled applications in high-contrast cellular imaging, photodynamic therapy and antifungal treatments.

Colloidal Semiconductor Nanocrystals and Their Optical Applications publication trend

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

Technical terms

Colloidal nanocrystal: A nanometre-scale semiconductor particle synthesised in a liquid medium with size-tunable electronic properties.

Core–shell heterostructure: A nanocrystal architecture in which one semiconductor core is encapsulated by a shell of another semiconductor to improve optical performance.

Photoluminescence quantum yield: The ratio of emitted to absorbed photons, quantifying the efficiency of luminescent materials.

Heteroepitaxy: Epitaxial growth of a crystalline layer on a substrate of different composition, ensuring coherent interfaces.

Luminescent solar concentrator: A device that captures sunlight via luminescent materials and guides re-emitted light to photovoltaic cells.

Type I heterojunction: A band alignment where both electrons and holes are confined within the same region, enhancing emission efficiency.

References

1. Finely regulated luminescent Ag-In-Ga-S quantum dots with green-red dual emission toward white light-emitting diodes. Opto-Electronic Advances (2024).
2. Coherent heteroepitaxial growth of I-III-VI2 Ag(In,Ga)S2 colloidal nanocrystals with near-unity quantum yield for use in luminescent solar concentrators. Nature Communications (2023).
3. Gallium Sulfide Quantum Dots with Zinc Sulfide and Alumina Shells Showing Efficient Deep Blue Emission. Angewandte Chemie International Edition (2023).
4. Bandgap Tunable AgInS based Quantum Dots for High Contrast Cell Imaging with Enhanced Photodynamic and Antifungal Applications. Scientific Reports (2018).