Photosensitive polymer semiconductors

Abstract

Models of photogeneration of charge carriers and structural regularities of the photoeffect are analyzed for homologous series of the main classes of photosensitive polymer semiconductors and their donor-acceptor complexes with different sensitizers. The relationship between the chemical structure of polymers and their photophysical properties is studied on the basis of an analysis of the effect of the energy and spatial structure of the monomeric unit of a polymer and the complex molecules on the spectra of the quantum yield of carrier photogeneration. The existence of general regularities of changes in the quantum yield with changes in the parameters of the molecular structure is ascertained for the main classes of polymer semiconductors and donor-acceptor complexes. Comparison of the experimental results with the calculations on the basis of the structure-sensitive model of Onsager photogeneration made it possible to estimate the initial distances and the degree of charge transfer in the excited state of complex molecules and relate the obtained values of the dipole moments to the hyperpolarizability in nonlinear optical media formed on the basis of these polymers and complexes. The ascertained structural regularities of the photophysical processes make it possible to predict the ultimate quantum yield of photoprocesses in polymer organic semiconductors and their molecular complexes, as well as the ultimate value of photosensitivity of recording media on their basis.