In order to find the band gap, I plotted a tauc plot of a UV absorption data. The Tauc plot contains two slopes as shown in the figure. Kindly tell me how to obtain the correct optical band gap from that data. I am confused which slope ( lower or higher) will give the correct data.
Hi, have you considered that your material might have two different band gaps? Have you checked it's structure? Different polymorphs of the same chemical compound have different band gaps, see for instance our latest paper for anatase and rutile TiO2:
https://www.researchgate.net/publication/380281765_Anatase_and_rutile_nanoparticles_in_photopolymer_3D-printed_nanocomposites_Band_gap-controlled_electron_interactions_in_free-radical_and_cationic_photocuring
If it is this case, the band gaps in the Tauc plot should be treated separately.
Hello, I'm a bit concerned about the Y axis of your plot. Are you sure about your absorption coefficient calculation?
Agree with Dr. Petr Petr Lepcio , it seems like a material with two difference energy gap. If you are sure that it must a single-gap semiconductor, you should give more information about this.