Hi, so I am currently working on carbon materials (graphene, graphitic carbon nitride) and would like to determine the bandgap of my materials. From my understanding graphene should not have a bandgap or at least it is near zero and graphitic carbon nitride which is a semiconductor should give me 2.7eV.
I have tried using absorption data for plot the Tauc plot but I am kind of stuck on determining the absorption coefficient (alpha) for alpha*hv. I am wondering how do I determine this alpha value if my sample is in liquid form. Tried a few methods online such as below and I still get an inaccurate bandgap
alpha = 2.303*absorption/ width of vial
alpha = 2.303/ width of vial / concentration of sample
Also, are they any other methods to determine bandgap energy from absorption data other than using Tauc plot?
Dear Adriel Yan Sheng Tan ;
You can calculate the molar absorbance using the standard equation of Beer-Lambert for absorbance; A = ɛ.l.C. Where A represents the amount of light absorbed by the (chemical solution) sample at a given wavelength, ɛ represents the molar absorbance coefficient, l represents the path length of light through the solution, and C represents the molar concentration. as detailed in the reference;
https://www.edinst.com/blog/the-beer-lambert-law/
Hi Adriel Yan Sheng Tan,
Hope the following videos might be helpful to you:
1) https://www.youtube.com/watch?v=HM4lzO9xrCk&ab_channel=PHYSICSINSIGHT
2) https://www.youtube.com/watch?v=tbyJjCMkDtc&ab_channel=NanoWorld
3) https://www.youtube.com/watch?v=u-chJAM73p0&ab_channel=nanotutes
Hi Mr. Adriel,
I would recommend the second video shared by Mr. Samit.
I have been working with graphitic carbon nitride and as I don't have access to a UV DRS instrument I also tested my samples as suspensions in a UV spectrometer. I then followed the video to analyze my data and determine the band gap.
I synthesized my g-CN from urea and got a band gap of 2.8eV which is expected for g-CN synthesized from urea.
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