Fig. 2: Orientation distributions of C545T in PMMA.

a Illustration of the complementary-polarisation excitation conditions used for DOPI. Each configuration is characterized by the linear polarisation state of the excitation beam, which is parallel or perpendicular to the plane of the films (labelled H and V, respectively), and its direction of propagation along the XZ or YZ planes (labelled X and Y, respectively). b Examples of DOPI patterns measured with the excitation condition shown to the left of each panel. All measurements shown are for the same field of view. The best-fit optical simulations are shown for comparison. The patterns strongly depend on the polarisation of the laser beam. A representative pattern seen under HY, VX, and VY excitation is marked by a white circle. For visualisation purposes only, an anisotropic background (coarse Gaussian filter) was subtracted from the experimental data to improve contrast. c Orientation distribution of polar angles for all detected C545T emitters. The distribution approaches the isotropic limit for large angles, but clearly deviates at smaller angles. d Schematic of a spin-coated film composed of C545T molecules dispersed in the transparent host PMMA. Horizontal dotted lines mark the different z positions used for optical simulations. e Histogram of polar angles for emitters at different vertical positions (z) within the film. The orientation distributions are different for each z value; this is also reflected in different anisotropy factors for each sub-ensemble.