Shape and optical anisotropy of colloidal semiconductor nanoplatelets and their application in light emitting diodes

Abstract

Colloidal semiconductor nanoplatelets (NPLs) are two-dimensional nanocrystals that are as thin as a few atomic layers and grow from several to several tens of nanometers in the lateral direction. NPLs exhibit the 1D quantum confinement effect in their thickness direction. As a result, they have unique optical and electrical properties. Especially, NPLs have optical anisotropy induced by their structural anisotropy. NPLs have linearly polarized emission along their long-axis, and have in-plane oriented transition dipole that emits directed light in a direction perpendicular to the surface. These properties are useful for the light emitting device and thus NPLs are one of promising materials for next generation display. This study focused on the shape and optical anisotropy of colloidal semiconductor NPLs and their application in light emitting diode. First, mechanism of anisotropic lateral growth and morphology control is suggested. Next, effect of shape anisotropy on the polarized emission from NPLs and the origin of shape dependence of polarization is studied. In addition, heterostructured NPLs with tunable emission in visible range were synthesized via cation exchange and applied in light emitting diodes.