According to TADF papers, the TADF materials possess an energy gap between the lowest singlet (S1) and triplet (T1) excited states that is sufficiently small (ΔEST between S1 and T 1 is less than 0.1 eV) to generate singlet excitons by thermal up-conversion of triplet excitons even at room temperature.
Generally, 1 eV is about 8000 cm-1 and 300 K is about 200 cm-1. So, 1 eV is about 12000 K and 0.1 eV is about 1160 K.
If TADF phenomenon occurs by the thermally assisted, how the TADF materials obtain the high temperature to transfer from T1 to S1.
For example, 2CzPN has ΔEST 0.09 eV that is about 1044.4 K and the TADF phenomenon occurs1.
Ref 1. Organic Electronics 2013, 14, 2721.
I have searched the papers about the temperature stability of 2CzPN and how to obtain the energy correspond to 0.09eV but I could not find anything.
The questions are
1. How to obtain the high energy (0.09 eV, 1044.4 K) to take places the TADF phenomenon in OLED.
2. Is there any other factor to occur to transfer from T1 to S1 that I don't know?
If let me know, I really appreciate.
The equilibrium (room) temperature is not the same as the temperature of the individual exciton. Additionally, the excitons have a certain attempt frequency to overcome the energy barrier, which they do with a likelihood that scales with a Boltzmann factor.
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