Room temperature single-photon sources are desirable for a variety of applications, rang- ing from quantum key distribution to building a standard to measure the luminous intensity of a light source [1, 2]. Solid state systems are especially appealing, not only because they are easy-to-use but also because of their potential for integration and scalability. However, most solid state emitters suffer from a limited photostability. So far only nitrogen-vacancy centers in diamond [3] and terrylene molecules in a para-terphenyl host [4, 5] have shown at room temperature stable single-photon emission over extended periods of time. Several years ago we discovered that terrylene is also extremely photostable in a crys- talline p-terphenyl film as thin as 20 molecular layers [6], which protects the molecule against quencher agents such as oxygen [7]. Doping single emitters into thin films has several advan- tages, especially in the context of single emitter experiments. First, background fluorescence is strongly suppressed due to the optimized ratio between emitter and matrix. Second, thin films are inherently compatible with nanostructures such as plasmonic waveguides, since the emitter is by definition in the near-field. Furthermore they can easily be integrated into mi- crocavities, either as part of a layered structure in a linear cavity or via evanescent coupling to a whispering-gallery resonator or a photonic crystal defect cavity. In this paper we investigate Dibenzoterrylene (DBT) molecules, which have been previ- ously studied in crystals at cryogenic temperatures [8–11]. Here we report on the fabrication of ultrathin crystalline anthracene (AC) by a simple spin coating procedure on glass cover slides. To produce the desired films, we prepared a solution of AC in diethyl ether with a concentration of 2 . 5 mg/ml and added 10 µ l/ml of benzene. The latter serves to improve the quality of the crystals obtained from the spin-coating process. DBT was then dissolved in toluene to obtain a 10 µ M solution, which was further diluted by a factor of 100 with the AC/diethyl ether mixture. Then we spin casted 20 µ l of the solution containing AC and DBT onto a glass cover slide. With a two-step process (30 s at 3000 RPM followed by 20 s at 1500 RPM) on a commercial spin coater we obtained areas with crystalline islands that covered several mm 2 of the substrate. Figure 1 (a) shows an optical polarization microscope image of a typical sample area, containing both film and bare glass regions. The contrast between glass and crystalline film is very low since one of the main axes of the anthracene crystal is aligned with the polarization vector of the incoming light. In Fig. 1 (b) the same portion of the crystal is rotated by 45 ◦ . In contrast to the amorphous glass the crystal shows some birefringence. As a result, the polarization vector of the transmitted light is rotated 2