What are the procedures to obtain optical absorption coefficient from PL data of a given semiconductor film? How PL data differs from the UV-Vis-NIR absorption spectroscopy data? Which one is better and with what respect?
PL is measured from electronic transition from higher to lower states. The transition emits photon.
Optical absorption is measured from electronic transition from lower to higher states. The transition absorb photon.
You can consider to read our paper discussing both terms.
https://www.researchgate.net/publication/330015970_Tuning_the_point-defect_evolution_optical_transitions_and_absorption_edge_of_zinc_oxide_film_by_thermal_exposure_during_molecular_beam_epitaxy_growth
In an idealised 2 level system, the Einstein co-efficients describing absorption, spontaneous and stimulated emission can be related. However, in real systems, defects, electron-phonon coupling, colounb interactions etc. mean it is difficult to relate them directly.
Dear Professor Byrne,
Thank you for your reply, and I am glad to let you know that it is closely related to my question. An absorbing material luminates photons. At the higher photon energy (X axis) of PL spectrum it is not possible to account for the absorption coefficient, since the material tends to reabsorbs the emitted photon having energy greater than its band gap. However, at the lower energy range, the PL spectrum essentially luminates photon having energy in the near band gap energy and also in the sub-band gap region. The absorption in the band edge and in the sub band gap optical absorption region arises due to several factors, such as, electron-phonon coupling to exciton-phonon interaction to electrostatic potential fluctuation to band gap fluctuation to defect assisted optical transitions (depending upon the material we are dealing with). And my exact query is how such PL spectrum in this lower energy range can be utilised to get an accurate information about Urbach absorption and related parameters, and thus an insight about the crystalline order of the semiconductor film (inorganic, organix or hybrid perovskites)? Thank you,
Check the following paper:
Article On conversion of luminescence into absorption and the van Ro...
Dear Dr. Saigal,
Thank you very much for your reply and the attached paper.
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