Semiconductor structures having a nanocrystalline core and nanocrystalline shell pairing compositional transition layers are described. In an example, a semiconductor structure includes a nanocrystalline core composed of a first semiconductor material. A nanocrystalline shell composed of a second semiconductor material surrounds the nanocrystalline core. A compositional transition layer is disposed between, and in contact with, the nanocrystalline core and nanocrystalline shell and has a composition intermediate to the first and second semiconductor materials. In another example, a semiconductor structure includes a nanocrystalline core composed of a first semiconductor material. A nanocrystalline shell composed of a second semiconductor material surrounds the nanocrystalline core. A nanocrystalline outer shell surrounds the nanocrystalline shell and is composed of a third semiconductor material. A compositional transition layer is disposed between, and in contact with, the nanocrystalline shell and the nanocrystalline outer shell and has a composition intermediate to the second and third semiconductor materials.