Quantum-Confined Nanostructures for Smart Optoelectronic and Theranostic Applications

Semiconductor quantum dots and their elongated zero-dimensional (0D) and one-dimensional (1D) counterparts are a major area of interest in solid state physics, materials chemistry and modern optoelectronic engineering. The electronic density of states (DOS) of these nanomaterials vary widely from continuous bulk bands to a structural and composition-dependent DOS and are 3D confined below the exciton Bohr radius. This review summarizes recent advances in both theoretical modelling of quantum confinement and synthetic paradigm of colloidal synthesis, hydrothermal synthesis, surface passivation by multi-shells and multidimensional structural heterostructuring (seeded nanorods). Importantly, we confront the use of alternative mirror boundary conditions in the context of the effective mass approximation to resolve discrepancies in the prediction of emission energies in the past. Lastly, the review contrasts the dual translation of these engineered architectures to next-generation optoelectronic circuitry (such as thin-film solar cell configurations, memristors, logic gates and deep-ultraviolet photodetectors) and multi-modal biomedical theranostics, which highlights remaining issues around heavy-metal toxicity, ligand-mediated charge transport barriers and physiological clearance kinetics.