Light in organic semiconductors in response to an external action (current transmission) by the phenomenon of thermally activat delay fluorescence (TADF). Fight for electrons If we imagine that electrons in atoms are a kind of currency, then there are “rich” (electron-donor) and “poor” (electron-acceptor) atoms. Scientists artificially construct a molecule in which the “rich” and “poor” parts are separat and maximally isolat from each other. Under the influence of electricity or light, the “flame of revolution” flares up – a struggle for electrons arises between “rich” and “poor” atoms.
When a molecule has such a structure
It leads to the appearance of an exciton – an excitation Switzerland Phone Numbers List state when the electron is in the “hole” of the acceptor. Accompanying this struggle are flashes of light (the result of the decay of singlet excitons) and heat (the result of the decay of triplet excitons), it is necessary to turn triplet excitons, which make up 75% of all emerging excitons, into singlet ones, Konstantin Ivanov, 2nd year postgraduate student, Faculty of Natural Sciences, Novosibirsk State University: “The energy difference between a singlet and a triplet state is like the number of steps on a flight of stairs between floors (how much energy do you ne to expend to go from one state to another.
The singlets ruce the number of steps
If the difference is large, then there are many steps, and USA CFO there is not enough energy for the transition. If the difference is small, the transition requires very little energy, which can be obtain literally from the environment – from vibrations of molecules, which are determin by the temperature of the environment. Accordingly, in order to obtain fluorescence with an efficiency of 100%, we “raise” the triplet levels closer to ) so that the triplets easily (with less energy consumption) “jump” into singlets and begin to emit light. Due to the fact that the singlet state exists only for a nanosecond, and triplets live.