Alignment of Quantum Rods to form a polarized emitter

J. Niehaus, S. Becker, T. Jochum, H. Weller
Fraunhofer CAN,
Germany

Keywords: quantum dot, quantum rod, polarized emission, alignment, display

Summary:

We will show single particle measurements to prove the polarization of light emitted by a quantum rod. We have investigated the influence of different factors like length and emission color on the degree of polarization. Based on these results we have optimized the synthesis of the nanorods for the alignment experiments. We have used two different approaches to cause an alignment of these rods on a macroscopic scale. First we applied an outer mechanical force to a particle polymer compound. We will show results obtained with different experimental settings. One of these results is shown in figure 1. It can be seen that a preferred orientation is caused, but the ratio of light emitted parallel to the preferred orientation to light emitted perpendicular is not satisfying. Second we have applied an outer electric field to align the rods due to their dipole moment. We have performed experiments with pure particle films as well as particles in polymer. For these experiments the particles were dispersed into the monomer and the electric field was applied prior and during UV curing. One of these results is shown in figure 2. It can be seen that this approach leads to a high degree of alignment on a macroscopic scale. This concept might be suitable to form polymer sheets with polarized emission for the use in display applications.