Spatial confinement, self-polarization and exciton–phonon interaction effect on the location of exciton line in lead iodide nanofilms

Abstract

Theoretical investigation of the spatial confinement, self-polarization and exciton–phonon interaction influence on the exciton state in plane double nanoheterostructure (nanofilm)–lead iodide in polymeric matrix is performed within the effective mass approximation for the electron and dielectric continuum for the phonons in the framework of infinitely deep single quantum well. It is shown that spatial confinement is the dominating feature determining the energy of the bottom of exciton ground band and its binding energy. The relationship of two others depends on nanofilm thickness: in ultrathin films the influence of self-polarization effect is essentially bigger than the role of exciton–phonon interaction.

Excitonic linewidth of organic quantum wires generated in reduced dimensionality matrices

“…A physical understanding of the origin of the observed energy shift can also be related to electrostatic effects. [39][40][41] Excitonic energies include two fundamental Coulombic contributions, the self-energy which increases the bandgap and, as mentioned above, the binding energy which decreases it. Passing from bulk crystals to films is equivalent to removing the half top space of the surrounding matrix of the dielectric constant e m (for the glass substrate e B e m and there is no perturbation expected).…”

Frequency spectrum and group velocities of acoustic phonons in PbI2 nanofilms

“…As a result, a number of works have been published in recent years, in which the results of both experimental and theoretical studies of various properties of ultrathin films of lead iodide are presented. In particular, the structure of the phonon spectrum and regularities of the heat transfer phenomenon were studied in works [5][6][7], and the transformation of the energy spectrum of the electronic system due to its interaction with optical phonons and changes in the exciton absorption band in such structures were studied in works [8][9][10].…”

“…To construct dispersion curves in such structures, numerical calculations are usually used (see, for example, [11,12]), and when calculating quantities that characterize a phenomenon or process, are limited to regularities valid for bulk (three-dimensional) crystals. However, to consistently describe the electron-phonon interaction, it is Frequency Spectrum and Group Velocities of Acoustic Phonons in PbI2 Nanofilms 479 necessary to use functions that describe the dispersion dependences for all branches of the phonon spectrum (see, for example, [8][9][10]13]). Thus, the problem of establishing such functions is relevant for the development of the theory of electron-phonon interaction in nanostructures.…”