It is interesting that peoples here suggest opposite variants: that the higher binding energy increase and decrease the exciton lifetime. They are both correct but for different cases.
To explain let's shift to recombination rates (value inverse to the lifetime). There are two rates: radiative (exciton emission) and nonradiative (exciton dissociation ). The higher exciton binding energy increase the radiative rate and decrease nonradiative rate. The overall lifetime will depend on the ratio between radiative and non-radiative processes.
Simplified: for material with high PLQY higher binding energy decrease the lifetime and other way around for material with low PLQY higher binding energy increase the lifetime
I think you should refer to the time-energy uncertainty relation: deltaE*deltat>=hbar/2.
Dear Fu,
The exciton radiative lift time is inversely proportional to the Binding Energy. you just refer PHYSICAL REVIEW B 85, 045207 (2012).
Hope it helps u.
Hi Fu, It is important to note the difference between exciton energy and exciton binding energy, even though these are related. The exciton binding energy is a measure of stability of the electron-hole pair. So for an exciton with high binding energy, it is less likely to be scattered by lattice vibrations to free charge carriers or undergo conversion to free charge carriers due to the presence of impurities or defects. Consequently, the exciton lifetime will be high compared to that of an exciton with weak binding energy. This is an important attribute for electronic applications because an exciton with long lifetime possess several properties that are suited for device operations.
Yes. The exciton binding energy can be found out by subtracting the exciton energy from the sum of the energies of the electron and the hole. An excton will be more stable if its binding energy is larger, because in that case a stronger interaction is required to break the electron-hole pair. Thus one would expect an exciton to have a larger life time if it has a larger binding energy.
- Badges
- Science topic
- Similar topics
- Physics
- Condensed Matter Physics