Nanoplatelets are atomically precise materials with a quantum well electronic structure, but produced in colloidal solution using wet chemistry. This presentation will discuss the use of nanoplatelets and their heterostructures, both in-plane and out-of-plane, for interband and intraband optics. In particular, the combination of large oscillator strength, atomic precision of thickness, and suppressed multiexciton nonradiative processes makes nanoplatelets exceptionally monochromatic emitters and promising gain media. Exploiting the quantum well structure, narrow polarized intersubband transitions can be tuned through the near-infrared and, under the right excitation conditions, produce unipolar optical gain similar to quantum fountains. Sandwiching a two-dimensional confinement potential between concentric spheres produces a distinct geometry--the quantum shell. Although this geometry reduces the oscillator strength of excitonic transitions, it further reduces multiexciton interactions, enabling long gain lifetime, wide gain bandwith, and exceptionally bright and stable scintillation properties.
