Hello everyone,
To date I’ve been calculating bandgap energy (BGE) from cyclic voltammetry (CV) measurements, as a difference between oxidation and reduction peaks’ onsets. The organic compounds I am currently testing exhibit more than one current peak, both in anodic and cathodic potentials. What is more, not all of those seem to be reversible processes (e.g. cyclic voltammogram curve exhibit two oxidation current peaks – overlapping within “positive” potential values – but only one reduction peak). I did differential pulse voltammetry (DPV) measurements, and for the case described above there are actually two perfectly shaped pairs of current peaks.
Problem: not all DPV current peaks overlay with CV’s half-wave potentials. This generates complications with determining the bandgap energy. For some compounds the difference between BGE determined from DPV and CV measurements is negligible; but for other compounds this difference is on the order of even 0.5eV.
Potential of reference electrode was stable during performed measurements, and purity of solvent (DCM) and supporting electrolyte (TBAP) was confirmed prior to each compound measured.
Best,
Hubert
I can provide you with an answer if you want to calculate the direct or indirect band gap using the Tauc plot method
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