PL intensity will explain the type of recombination occurring in materials. How do we confirm the increase in intensity will enhance the radiative recombination?
For an ideal sensitizer, Fluorescence intensity shoud be more. Because, non-radiative decay is more faster than radiative one. If compound is more fluorescent, the excited state lifetime of the sensitizer would be more and it would be beneficial for other photophysical preocesses like ekectron injection in DSSC. (This i have read somewhere and I am unable to find out the file for attaching here)
Photoluminescence measurements are often carried out on many kinds of photocells because it is a natural recombination process competitive to the required separation and photocurrent generation. The goal is to reduce the photoluminescence as much as possible.
I have attached the thesis of Dr. Elene Longe. Please see the page no: 42. All the best.........
PL spectroscopy doesn't necessarily tell you the specific type of recombination taking place within the bulk of your Solar cell on its own (Speaking for organic solar cells). You may be able to identify which regions (in terms of wavelegnth) of the spectrum belong to which molecules or chemical bonds and by using other techniques such as E.Q.E. you could get a better idea. So if we consider the radiative recombination (i.e. Bimolecular recombination) or non-radiative (Trap assisted recombination SRH), it can be said that they will both be giving off some level of Photon upon recombination. therefore by only looking at the PL spectrum, it would be difficult to say if the recombination mechanism which has led to release/emission of photon belongs to which type of recombination. If you do some studies on the mobility, and recombination states for your specific material you are using, and combining it with your PL results, you should be able to see a much more clearer image of why your PL intensity is increasing and to which recombination mechanism it belongs.
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