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Information × Registration Number 0225U000753, (0123U102728) , R & D reports Title Persistent luminescence - a new paradigm for innovative applications of organic semiconductor systems popup.stage_title Дослідження механізму рекомбінації носіїв заряду в системах з О-ДПЛ за допомогою вимірювання кінетики загасання рекомбінаційної ізотермічної люмінесценції при різних температурах, встановлення зв’язку динаміки рекомбінації зарядів з параметрами розподілу пасткових станів. Head Kadashchuk Andrii K., Кандидат фізико-математичних наук Registration Date 18-01-2025 Organization Institute of Physics of National Academy of Sciences of Ukraine popup.description1 The main goal of the research is to comprehensively study the mechanisms of physical processes that cause the emergence of long-term persistent luminescence of organic systems (O-PL), which means the "accumulation" of energy in photoinduced long-lived states with spatially separated charge pairs and is a new phenomenon for organic semiconductors, forming a promising area of their application. The elucidation of the complex mechanism of O-PL is aimed at improving the characteristics of such organic systems for use in flexible optoelectronics devices. popup.description2  The decay kinetics of isothermal recombination luminescence (IRL) in the temperature range from 5 to 400 K in model composite systems with shallow charge carrier traps (PVK polymer matrix doped with trinitrofluorene derivatives) and with deep charge traps (DPEPO matrix with MTDATA doping) have been studied by nonstationary spectroscopy and thermally stimulated luminescence (TSL). Extremely long-lasting decay of the IRS luminescence is observed in such systems for several thousand seconds after photoirradiation of the sample, and the IRS kinetics is described by a hyperbolic law, with the power law (Beckerel coefficient) decreasing with temperature rise from the classical value of 1 at 5 K to a minimum value of 0.6 at 180 K and 300 K, respectively, for the system with shallow and deep traps. This behavior indicates a significant slowing of the recombination rate at some optimal temperature, which depends on the depth of the traps and correlates well with the maximum position of the TSL band in such systems. For the first time, it was demonstrated that the kinetics of IRL decay at room temperature in a system with deep traps also slows down significantly with increasing irradiation time of samples from seconds to one hour, while the relative fraction of charge carrier pairs separated by a large distance gradually increases. Thus, to obtain long-term persistent luminescence (OLPL), it is necessary to irradiate the samples for a long period of time, at least 30 minutes. The Monte Carlo simulations and theoretical calculations within the framework of the analytical model of recombination/dissociation of the geminal charge pairs in disordered organic systems confirmed the experimentally observed slowdown in the recombination rate and showed that the LPL is due to the very slow diffusion of charge carriers, which is based on their hopping transfer along the local levels of traps. Product Description popup.authors Vakhnin Oleksandr Yu. Kadashсhuk Andrii K. popup.nrat_date 2025-01-18 Close