Turyk P. Organic light-emitting nanostructures with long-term fluorescence for optical sensors.

The thesis is directed at the creation of high-efficient organic light-emitting structures, including structures based on phosphorescence and thermally activated delayed fluorescence (TADF), as well as on the implementation of hybrid structures with dual-channel energy transfer from the organic exciplex interface to inorganic nanoparticles for radiation sources of optical sensors. In the work on the basis of complex studies of newly synthesized materials developed highly effective phosphorescent organic light-emitting structures based on derivatives of carbazole and indole (enabling voltage from 2.4 V, current efficiency to 38.6 cd/A, external quantum efficiency of electroluminescence to 18%), exciplex organic light-emitting structures based on derivatives of carbazole and triazine (enabling voltage from 5.2 V, current efficiency to 15.51 cd/A, external quantum efficiency of electroluminescence to 6.84%), as well as for the first time implemented organo-inorganic structure based on the introduction of BaZrO3 perovskite nanoparticles in the exсiplex environment TCTA/Bphen (enabling voltage of 6.6 V, current efficiency to 3.88 cd/A, external quantum efficiency of electroluminescence of 1.26%). Thermal studies have confirmed that new carbazole-indole host-materials can be used to obtain thin amorphous layers on substrates with high values of glass transition temperature from 89°C for Ноst 1 to 130°C for Ноst 3. From the absorption spectra of the host-materials, two bands with maxima of 293 nm and 342 nm were detected. They can be attributed to π-π* transition of fragments of 9-phenylcarbazole. The width of the band gap was estimated by linear approximation of the start of absorption spectra and equal to 3.53 eV for all materials. The host-materials showed the same Stokes shifts about 24 nm. Investigation of host-materials using cyclic voltammetry has confirmed that all materials are electrochemically stable. In addition, the potentials of ionization of solid films are estimated by the photoemission method in the air. The potentials of ionization of carbazole-indole host-materials are proportional (≈5.7 eV). It is shown that materials 1-3CzNC absorb light in the ultraviolet part of the spectrum. The forms and range of wavelengths of the main absorption bands are almost proportional. Characteristic peaks are observed at 269 nm, 271 nm and 299 nm. Moreover, strips of lower intensity are in the long-wave region (325-360 nm). It was found that the difference in wavelengths between 1CzNC and 3CzNC is 0.17 eV. This effect is associated with more aminocarbazole units. The study of the exciplex-forming properties of 3CzNC material is described. Exciplex radiation of films 3CzNC:BPhen and 3CzNC:TPBi is far from the fluorescence of the 3CzNC film and the fluorescence of the used acceptors. To determine the TADF properties of the 3CzNC:BPhen and 3CzNC:TPBi mixtures, the photoluminescence intensity dependence of the laser flux was recorded. Since the inclination of the linear dependences of the intensity of photoluminescence on the laser stream for the investigated mixtures were close to 1, then the presence of TADF is confirmed. It is shown that in the spectrum of electroluminescence BaZrO3 there are three emission bands with maxima of 372 nm, 386 nm, 538 nm and a weak shoulder at 410 nm. With the aid of atomic force microscopy, it has been found that the surface of TCTA/BaZrO3 has a relatively low roughness, which is acceptable for the formation of light emitting structures. It was found that the organo-inorganic structure З (ITO/TCTA/BaZrO3/Bphen/Ca/Al) is characterized by the transfer of energy from the exciplex to BaZrO3 nanoparticles.