Temperature changes of the exciton transition energy in lead di-iodide nanofilms

Abstract

Abstract. Adduced in this work are the results of theoretical investigations devoted to the influence of spatial confinement effects, self-polarization of heterojunction planes and exciton-phonon interaction on values of the exciton transition energy in lead diiodide nanofilms placed into dielectric ambience (glass or polymer). The heterojunction is considered to be unloaded, nanosystem is modeled with an infinite deep quantum well and characterized by an essential difference between dielectric permeabilities in both sides of the heterojunction. Calculated in the work are dependences of the exciton energy on the nanofilm thickness and temperature. The results of calculations are in accordance with the known data of experimental measurements.

Temperature changes in the function of the shape inherent to the band of exciton absorption in nanofilm of layered semiconductor

“…In NF of the studied type with the thickness exceeding four layers of lead iodide, interaction with confined phonons is dominant [14]. In this case, with account of the quadratic dispersion law and changing summation by the variable …”

“…The model for the Wannier-Mott exciton in NF of layered semiconductor (medium 0) embedded into isotropic dielectric (medium 1) was considered in [14]. The heterojunction is considered here as unstrained, while QW is rectangular and, with account of dielectric nature of barrier medium, the infinitely deep one.…”

“…respectively, the state of free electron and free phonon, while int H -exciton-phonon interaction (EPI); their apparent look and peculiarities in the case of NF consisting of layered semiconductor are described in detail in [14,16], while offered in [13] is the method for finding the energy of quasi-two-dimensional exciton in NF as well as the function of its state. In the first approximation of the perturbulation theory, the exciton wave-function can be represented in the form of production Here, ν = (n e , n h , n, m), where n and m are quantum numbers that determine the states of 2D-exciton [17], n e and n h -states of electron and hole that create it.…”

“…Adduced in [14] are the results of theoretical investigations devoted to temperature changes in the energy of transition to the ground exciton state in a plain nano-film (NF) of 2H-polytype of lead iodide (2H-PbI 2 ) embedded into dielectric surroundings -borosilicate glass or ethylene-methacryl acid (E-MAA) copolymer. Availability of the method to calculate the exciton energy in NF enables to study temperature transformations in the shape of the exciton absorption band in this nanosystem.…”

“… n X 1 -quantity adduced in [14] that defines interaction of electron (in its ground state in QW (n e = 1)) with confined phonon being in the state with a quantum number λ with participation of n-th (n e = n) minilevel of carrier; ν(T) are the numbers of filling the phonon states: …”