A tight-binding calculation was presented to describe multiblock copolymers, such as [...-(PA)x-(PPP)y-...] composed of PA (polyacetylene) and PPP (poly(p-phenylene). It is found that a copolymer has a quantum well and superlattice characteristics, and evident is the effect of the composite lengths, the interfacial couplings and the electron-phonon interactions on the electronic properties of a copolymer. The quantum tunneling, the Franz-Keldysh effect and the quantum confinement can be generated under an applied electric field. These results were compared to those of traditional inorganic quantum well and superlattice systems.
A tight-binding model describing the xPPP/yPA diblock copolymer has been adopted.The ground states, doping states, configurations, electronic distributions and the types of excitations have been studied. It is found that the ratios and interfacial couplings of the components have effect on the properties of excitations in xPPP/yPA diblock copolymers. The interface between two homopolymers acts as an energy barrier which increases with the weakening of the interfacial coupling.
Copolymers which are synthesized by oligomers or homopolymers have quasi-one-dimen sional structures. A tight-binding model was suggested to study the organic quantum-well properties of triblock copolymers xPA/nPPP/yPA and xPPP/nPA/yPPP consisting of polyacetylene (PA) and poly(p-phenylene) (PPP). It was found that the electronic density in the lowest conductive state ( LU MO) could be tuned by the ratios of homopolymers and interfacial coupling. The spontaneous quantum tunneling effects will occur in triblock copolymer xPA/nPPP/yPA with the increasing interfacial cou pling.
