Excitons in Low-Dimensional Systems: Conjugated Polymers and Semiconductor Surfaces

ABSTRACTWe investigate the formation of excitons in low-dimensional semiconducting systems. To this end a recently developed ab initio approach is employed to determine the excitation energies and optical transition matrix elements of bound and unbound excitonic states. From these results the optical spectrum can be evaluated. We discuss two classes of low- dimensional prototype materials: conjugated polymers and a semiconductor surface. Due to the reduced dimensionality, the excitonic binding energies are much larger than in con- ventional semiconductors.