Defining of electron affinity of heterocyclic molecular semiconductors as per autocorrelation parameters of optical absorption spectra

Heterocyclic polycyclic compounds containing atoms of oxygen and nitrogen are promising materials for molecular electronics. A wide field of application of such compounds requires information on electronic structure, in particular, energy of electron affinity which along with ionizing potentials defines the processes of transport of electrons, bottom and upper boundary of band gap, energy of Fermi quasi-level, and output work. For heterocyclic molecular semiconductors containing atoms of oxygen and nitrogen a connection was found between electron affinity and integral autocorrelation characteristics of the optic spectrum in ultraviolet and visible spectrum based on the concept of absorption spectra as a complex of excited electron states in a strongly correlated electron system. The absorption spectra of molecules were registered in optically-transparent mediums using a spectrophotometer СФ-2000 with interval of 1 nm. We demonstrated that in the series of heterocyclic molecular mediums with growing integral autocorrelation characteristics of the spectrum the electron affinity increases as per quasi-linear law. The peculiarity of the electronic structure of heterocyclic compounds containing atoms of oxygen and nitrogen are the effects of strong exchange and Coulomb correlation interaction of electrons. These results are proved by data of experiments on registering the optical absorption spectra of heterocyclic molecular semiconductors in the range of 200-600 nm, as well as by quantum-chemical calculations using Hartree-Fock's methods. The obtained results are substantiated by statistical processing of data using the methods of least-squares and mathematical statistics. Based on the discovered patterns a method was developed on defining the electron affinity of heterocyclic molecular semiconductors. A method was developed which allows to assess electron affinity as per optical absorption spectra in ultraviolet and visible sprectra.