OPTICAL-PROPERTIES OF CONJUGATED POLYMER SUPERLATTICES PREPARED BY POTENTIAL-PROGRAMMED ELECTROPOLYMERIZATION

Photoluminescence (PL) spectra of thin films of pyrrole and bithiophen e copolymer with an alternating layered structure prepared by the pote ntial-programmed electropolymerization method were investigated. Band edges of thin films of the copolymers were estimated by optical and el ectrochemical method, and they were adopted to design a superlattice p otential profile of the alternating layered film. PL spectra of the co polymer films shifted to higher energies as thiophene fraction in the film decreased. This shift corresponded to band structure change. PL s pectra of the layered films, designed to be type II superlattices stru cture, shifted to higher energies as periodicity of the layered struct ure became shorter. This phenomenon is to be interpreted as a quantum size effect. The observed shift was explained by the Kronig-Penney mod el with 0.6m(e) (electron mass) of effective mass.