Tuning the Polarization and Directionality of Photoluminescence of Achiral Quantum Dot Films with Chiral Nanorod Dimer Arrays: Implications for Luminescent Applications

We examine the polarization state of photoluminescence of core/shell semiconducting nanocrystals coupled to periodic arrays of gold nanorod dimers. Here, we study the effects of changing the pitch of the periodic array, detuning the light emitter from the resonance of the array, altering the nanocrystal material, introducing a spacer layer, and modulating the refractive index of the underlying substrate on the direction and sign of the degree of circularly polarized photoluminescence emitted from the nanocrystal-metamaterial hybrid system. Angle-resolved measurements using a Fourier-space polarimetry setup show that nanocrystals coupled to the two chiral configurations emit circularly polarized light of opposite handedness at mirror symmetric directions, and each chiral nanorod dimer configuration favors a specific circular polarization. We find that the chiral optical response of the hybrid system is preserved for all the different modifications introduced to the original geometry. This work suggests that a broader range of materials and architectures of nanostructures can be integrated to change the direction and twist the polarization state of the photoluminescence of luminescent films.