Anisotropic optical emission of single CdSe/CdS tetrapod heterostructures: evidence for a wavefunction symmetry breaking

Semiconductor tetrapods are expected to exhibit isotropic optical properties due to their tetrahedral symmetry. We have investigated the optical polarization properties of individual CdSe∕CdS tetrapods of high structural quality. In contrast to the light absorption behavior, a pronounced anisotropy is observed in the optical emission. This unexpected result can only be explained by assuming a symmetry breaking in the electronic wavefunction. Calculations reveal that slight differences between the arm diameters induce the polarized emission and a decrease in the photoluminescence intensity.