External parameters such as temperature, pressure, and concentration are typically used to control chemical transformations in molecules and materials. Many classes of inorganic materials are also responsive to external stimuli, such as electric, magnetic, and electromagnetic fields. This Review article will explore examples of how light can guide the growth of metal and semiconductor nanostructures. Plasmon excitation in metals and electronic excitation in semiconductors mediate interfacial charge-transfer reactions to alter the growth rates of these materials at the nanoscale. Light-driven growth of inorganic materials provides a route to achieve morphological control over colloidal particles and nanostructured films for potential applications in solar energy conversion, photonic computing, and holography.

We demonstrate that the anion composition of ternary silver bromoiodide, AgBr1–xIx, nanocrystals determines their shape through the introduction of twin defects as the nanocrystals are made more iodide-rich. AgBr1–xIx nanocrystals grow as single-phase, solid solutions with the rock salt crystal structure for anions compositions ranging from 0 ≤ x < 0.38. With increasing iodide content, the morphology of the nanocrystals evolves from cubic to truncated cubic to hexagonal prismatic. Structural characterization indicates the cubic nanocrystals are bound by {100} facets, whereas the hexagonal platelet nanocrystals possess {111} facets as their top and bottom surfaces. Calculations based on first-principles density functional theory show that iodide substitution in AgBr stabilizes {111} surfaces and that twin defects parallel to these surfaces possess a low formation energy. Our experimental observations and calculations are consistent with a growth model in which the presence of multiple twin defects parallel to a {111} surface enhances lateral growth of the side facets and changes the nanocrystal shape. This new method to control nanoscale morphology based on anion composition provides a route to study structure–activity relationships in silver halide photocatalysts.

External parameters such as temperature, pressure, and concentration are typically used to control chemical transformations in molecules and materials. Many classes of inorganic materials are also responsive to external stimuli, such as electric, magnetic, and electromagnetic fields. This Review article will explore examples of how light can guide the growth of metal and semiconductor nanostructures. Plasmon excitation in metals and electronic excitation in semiconductors mediate interfacial charge-transfer reactions to alter the growth rates of these materials at the nanoscale. Light-driven growth of inorganic materials provides a route to achieve morphological control over colloidal particles and nanostructured films for potential applications in solar energy conversion, photonic computing, and holography.