Electro-optical properties of excitons in polydiacetylene chains

Abstract:

We show how to compute the optical functions (reflectivity, transmission, and absorption) of polydiacetylene chains diluted in their monomer matrix exposed to a uniform electric field in the chain direction, in the excitonic energy region. Adopting a model electron-hole potential, we derived an analytical expression for the effective chain susceptibility, which gives the optical functions. The resulting absorption shows excitonic peaks below the gap and Franz-Keldysh oscillations above the gap. The method has been applied for a 3BCMU polydiacetylene chain, showing a good agreement with experimental spectra.