Directed In Situ Crystallization of Anisotropic Perovskite Nanocrystals in Lyotropic Liquid Crystalline Polymer Templates for Linearly Polarized Emission.

Metal halide perovskite nanocrystals exhibit outstanding photophysical properties, yet controlling their orientational organization is essential for achieving anisotropic optical functionalities. Here, lyotropic liquid crystalline polymer (LLC-P) templates are designed to induce morphological anisotropy and crystallographic orientational order in CsPbBr3 nanocrystals. The shear-aligned, hexagonally ordered polymer framework consists of molecularly ordered polymer bundles, serving as an impenetrable template that guides the spatial organization of the perovskite phase on a macroscopic scale. These structural features play a crucial role in inducing the crystallographic orientation of the nanocrystals embedded within the template. Grazing-incidence wide-angle X-ray scattering (GIWAXS) confirms that this template-directed alignment translates into linearly polarized emission, with a dichroic ratio (DRE ≈ 4.29) and degree of linear polarization (DOLP ≈ 0.62). These optical responses reflect the preferential alignment of the nanocrystals and their associated transition dipoles within the anisotropic framework. The structural order parameter (Sstr) is highly consistent with the optical order parameter (Sopt), as described by the second-order Legendre polynomial (P2(cosα) ≈ 0.83). This strong structural-optical correlation demonstrates that polarized emission is governed by the structural ordering imposed by the template. This approach establishes a robust strategy for coupling anisotropic structural organization with polarized optical response in perovskite-polymer composite films.