Abstract A conductive boron-doped diamond (BDD) grown on a fused silica/quartz has been investigated. Diamond thin films were deposited by the microwave plasma enhanced chemical vapor deposition (MW PECVD). The main parameters of the BDD synthesis, i.e. the methane admixture and the substrate temperature were investigated in detail. Preliminary studies of optical properties were performed to qualify an optimal CVD synthesis and film parameters for optical sensing applications. The SEM micro-images showed the homogenous, continuous and polycrystalline surface morphology; the mean grain size was within the range of 100-250 nm. The fabricated conductive boron-doped diamond thin films displayed the resistivity below 500 mOhm cm-1 and the transmittance over 50% in the VIS-NIR wavelength range. The studies of optical constants were performed using the spectroscopic ellipsometry for the wavelength range between 260 and 820 nm. A detailed error analysis of the ellipsometric system and optical modelling estimation has been provided. The refractive index values at the 550 nm wavelength were high and varied between 2.24 and 2.35 depending on the percentage content of methane and the temperature of deposition.

Tris(8-hydroxyquinoline)aluminium with poly(N-vinylcarbazole) (Alq ₃:PVK) or polystyrene sulfonate (Alq ₃:PSS) were deposited by spin-coating on glass and silicon substrates. SEM measurements show that relatively smooth thin films were obtained. Fourier transform infrared measurements were performed to confirm the composition of the samples. The optical properties of thin films containing Alq ₃:PVK and Alq ₃:PSS were characterised using absorption spectroscopy and spectroscopic ellipsometry. It was found that the absorption spectrum of Alq ₃:PVK is characterised by four bands, while for Alq ₃:PSS only three bands are visible. The photoluminescence of the studied thin layers shows a peak with a maximum at about 500 nm. Additionally, cyclic voltammetry of Alq ₃ is also presented. Theoretical density functional theory calculations provide the insight into the interaction and nature of Alq ₃:PVK and Alq ₃:PSS excited states. Finally, the organic light-emitting diode (OLED) structure based on Alq ₃:PVK was fabricated and showed strong electro-luminescence with a green emission at 520 nm. The results of the device show that the ITO/PEDOT:PSS/Alq ₃:PVK/Ca/Al system can be useful for the production of low-cost OLEDs with Alq ₃:PVK as an active layer for future lighting applications.