Superlattice model to describe inter-molecular wave function overlap in polydiacetylene crystalline films

Blue shifts have been observed in both optical absorption and photoconductivity spectra for polydiacetylene (PDA) crystalline films with increased irregularity in molecular ordering. This behavior is interpreted in view of the overlap of π-electron wave function among one-dimensional PDA molecular wires. Kronig–Penney model is introduced to assess the overlap in terms of a change in the inter-molecular distance caused by the irregularity.