Quantum dots (QDs) are three-dimensionally confined semiconductor nanoparticles that have been extensively studied to meet the demands of modern applications. Among them, core/shell QDs have emerged as highly versatile nanostructures that integrate quantum confinement with engineered band alignment, offering superior optical stability, high quantum yield, and reduced nonradiative losses compared to bare QDs. Beyond chemical stability, the shape, size, and surface modifications of core/shell QDs critically influence their optical and electronic properties, thereby governing effective carrier confinement. By spatially separating the optically active core from a passivating or electronically engineered shell, core/shell architectures suppress surface trap-mediated nonradiative recombination and spectral diffusion, resulting in higher quantum yields, improved photostability, and tunable band alignments for charge and exciton confinement. These attributes position core/shell QDs as promising materials for next-generation technologies.
Two parallel approaches currently dominate technological progress. First, epitaxial self-assembled III–V core/shell heterostructures (e.g., InAs/InP, GaAs/AlGaAs variants) yield optically active, spin-addressable single QDs with steadily improving coherence and deterministic coupling to photonic cavities—key advances that enable single-photon sources and spin-qubit prototypes, with coherence times now reaching microseconds to milliseconds under optimized decoupling and material-growth strategies. Second, colloidal core/shell QDs (e.g., graded-alloy CdSe/CdS/ZnS and perovskite core/shell systems) provide solution processability, high brightness, and tunable band structures that support on-chip integration and scalable quantum-emitter arrays, though challenges remain in minimizing charge leakage and noise as well as enhancing surface/ligand stability.
In summary, core/shell quantum dots combine material-level strategies (band engineering, shell passivation) with device-level integration (cavities, photonic circuits) to provide a practical pathway toward scalable quantum emitters and spin qubits. Ongoing progress in growth chemistry, decoherence suppression, and heterogeneous integration will play a decisive role in shaping their impact on near-term quantum computing and quantum communication technologies.
