Solution processed multilayers of Alq$_{\mathrm{3}}$ molecules and TiO$_{\mathrm{2}}$ nanoparticles for hybrid Bragg mirror

Tris (8-hydroxy) quinoline aluminum (Alq$_{\mathrm{3}})$ is a small-molecule-based organic compound with a low index of refraction. It has been widely used as a superior material for organic light emitting diodes. Colloidal titanium dioxide (TiO$_{\mathrm{2}})$ is constructed of inorganic nanoparticles having a very high index of refraction. They have been commonly used in thin-film optics. Multilayer structures of Alq$_{\mathrm{3}}$ molecules and TiO$_{\mathrm{2}}$ nanoparticles are successfully fabricated from solution process and using spin coating techniques. A structure consisting of alternating organic/inorganic layers exhibited the properties of a distributed Bragg reflector (DBR). The peak of the reflectivity for the constructed DBR was chosen as 530 nm, at which the emission of Alq$_{\mathrm{3}}$ occurred. For this device, the reflectivity over 90{\%} can be obtained with as few as five periods of the structure. Fabrication process and optical properties of the structure are presented.