Optical band gap (Tauc plot)
Paste a UV–Vis spectrum as wavelength (nm) or photon energy (eV) against absorbance. Lattent builds the Tauc plot, finds the straight part of the absorption edge and extrapolates the band gap with its confidence interval.
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Questions
Direct or indirect?
Use direct allowed (r = 1/2) for ZnO, GaN, perovskites and most quantum dots; indirect (r = 2) for Si, TiO₂ (anatase) and many oxides. If unsure, try both and compare the straightness of the fit.
Can I use absorbance instead of α?
Yes. α is proportional to absorbance for a film of fixed thickness, which scales the plot but does not move the intercept.