To date, there has been significant progress studying the alignment of colloidal SC NRs in solution by AC electric fields as a strategy for producing functional materials with strong electro-optic modulation of optical anisotropy, typically in the 0.5-10 kHz frequency regime. The underlying mechanism is based on torquing the electrostatic dipole moment in NRs-largest along the long axis-by means of an externally applied electric field, leading to collective alignment of NRs parallel to the field direction. Previous reports have attributed the electrostatic dipole moment in cadmium chalcogenide NRs to an intrinsic permanent dipole moment arising from their noncentrosymmetric wurtzite crystal structure. Additionally, in the presence of an external electric field, induced dipole moments may also contribute to the overall electrostatic dipole moment along the long axis. The alternating magnitude of an applied AC field causes the NR ensemble to oscillate between aligned and randomly oriented configurations. Since NRs preferentially absorb light with polarization that is parallel to their long axes, switching between aligned and random configurations can give rise to a periodic change in absorbance, up to a relative change of 53% as demonstrated by Mohammadimasoudi et al. In a typical geometry (see Figure ) where the sample is excited with light that is polarized perpendicular to the electric field, the absorbance of the sample decreases with increasing degree of alignment. This manifestation of the AC field-driven ordering in the timedependent absorbance signal has been used to quantify the alignment in a NR ensemble, with the highest possible degree of order targeted as most beneficial for optoelectronic applications.