I am preparing film on glass from the commercial materials following reported protocol. UV-vis absorbance is getting perfect results according to literature but PL response is not achieved in single peak between 700-800. I tried various excitation wavelength ranging from 465 nm to 630 nm. Please share some experience if someone know.
Dear Keval
When you use a commercial PL spectrophotometer, make sure that you need to do the spectrum response correction since each optical components have their diffetent response to the optical frequencies or wavelengths. A lot of researchers forget doing this and only use the raw signals from the measurements. It occurs very often in the publications due to inconsistent PL results from the same condition. This problem is not severe in the blue region due to the less correction curves from optical components. It has a big impact on the red region.
If you want to have proper PL measurements, you need to do calibration on the instrument to get a correction file. Then use the correction data to calibrate your sample data if your measurement results are not corrected.
Hope it helps
Best wishes
Xuhua
Please try from 300 and then 310 ,320 etc.. do this quick ,then
when you find any change in the absorption you can go above or lower until yoy fixed the best wavelength
Hi Keval,
MAPbI3 thin films are generally good light absorbers but not good emitters (the reason MAPbI3 thin films have very low or undetectable photoluminescence quantum yields). That's why, you are able to collect good absorption spectra but not good PL spectra of the MAPbI3 thin films.
Your problem, you are using narrow slit width (say, less than 50 micron) for collecting photons. In this case, you will not see any PL spectra because your spectrometer is able to collect very few emitted photons. To get good PL spectra, you need to collect more emitted photons. So, try 100 micron slit width or higher slit width with higher integration time, you will get nice PL spectra of the films.
Hope this will help you!
Best,
Aslam
Hi Keval,
I excite the sample with 420nm and got the Pl emission from MAPbI3 thin film prepared on the glass substrate using a hot casting technique.
Hi Keval,
I recommend increasing exposure time/slit width to be able to see your signal, also you may need to increase your power depending on what kind of counts you're seeing. You also shouldn't need to change excitation wavelength much, I'd recommend keeping it below 550. Good luck!
Best,
Boe
When PL is weak, I recommend first not to use any spectrophotometer, but a broad band detector and low-wavelength cut filters. Eventually, low temperatures can help. Once detected, if any, you can proceed with analyzing the spectrum.
Dear all thank you so much for sharing your knowledge. I get PL measurement very well from your valuable suggestions.
Hi Keval, I think you should get the solution from the previous answers. However, I would like to suggest better using a Raman micro-PL to study the PL response. I faced the same problem and finally, the solution came from the use of the commercial Raman micro-PL.
Best,
Kamal
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