Shape control in the synthesis of colloidal semiconductor nanocrystals

Semiconductor nanocrystals (NCs) represent an important class of building blocks materials for next-generation solution-processed optoelectronic devices. The ability to control the shape and thus the spatial extent of electron and hole-wave functions enables new opportunities for materials design and performance enhancement of NC-based devices. For example, rod-shaped CdSe NCs have shown improved power conversion efficiency compared to their spherical counterpart in photovoltaic devices. Over the past three decades, the synthetic control over semiconductor NCs has grown in sophistication, and has now reached a stage where a rich variety of morphologies has been demonstrated, including many convex and concave polyhedral shapes, branched (e.g., tetrapods), and cage-like morphologies. In this chapter, we provide a survey of different families of colloidal semiconductor NCs, with an emphasis on key principles underlying synthetic control.