Oscillatory Structure in the Electroabsorption Spectrum of π-Conjugated Polymer Thin Films: How to Identify the Franz–Keldysh Oscillation

Abstract

The nature of the oscillatory structure observed in the electroabsorption spectrum of highly ordered thin films of poly(9,9-dioctylfluorene) has been investigated and compared with that of the theoretically expected one-dimensional Franz–Keldysh (FK) oscillation. Although the observed oscillatory structure is not an FK oscillation, there are some similarities. From this comparison, we have discovered some features that can be used to distinguish whether the oscillatory structure is an FK oscillation, which include the field dependence of the oscillatory structure measured at four times the frequency of the applied electric field.