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Information × Registration Number 0213U002297, 0112U005394 , R & D reports Title Mechanism of low-threshold noncoherent up-conversion in novel composite organic materials for optoelectronics. popup.stage_title Head Kadashchuk Andrey Konstantinovich, Registration Date 23-01-2013 Organization Institute of physics NASU popup.description2 The aim of the research project was the study of the nature of low threshold up-conversion of light in model composite material and the characterization of new materials promising for up-conversion. The comprehen-sive measurements of the steady-state absorption and emission spectra, the luminescence ones with pico- and nanosecond signal resolution at different temperatures within the wide range of exciting energies, and photo-induced absorption spectra by the pump-probe method with femtosecond time resolution were made for the model material composed of the matrix of the diphenile-antracene doped with the platinum complex of porphyrin, and for its components in solution and solids as well. As a result, there were obtained the data about the parameters of excited states and their nature for this composite and its components, and in the issue, the energy-level diagram was built and the scheme of energy transfer for optical excitations in the composite was proposed. In the films of this composite at the room temperature, the noncoherent up-conversion of light was revealed under the low-intensity excitation through the absorption band of admixture. At that, the up-converted emission was a delayed fluorescence of matrix that arose due to effective triplet-triplet annihilation sensitized via dopant. The intersystem crossing in platinum complex of porphyrin was ascertained to pass very quickly for the time shorter than 80 fs, while the transfer of the triplet excitation from admixture molecule to matrix occurred during the tens of nanoseconds. The comprehensive study of surface morphology by ASM method and luminescence spectra was carried out for the series of thin films of para-sexiphenile (PSP) grown by hot-wall epitaxy on the mica crystals at various substrate temperature. There was determined that dimensions of PSP needle-like nanocrystallites depend crucially on the substrate temperature during the film growth. By optimizing this parameter it is possible to attain the maximal length (and the maximal length-to-width ratio) for PSP crystallites that is necessary condition for the production of blue emission with high yield and polarization ratio, which is especially important for application of PSP as highly efficient matrix for the study of the noncoherent up-conversion of light. Product Description popup.authors Вахнін Олександр Юрійович Кадащук Андрій Костянтинович Фіщук Іван Іванович popup.nrat_date 2020-04-02 Close