## 1 Introduction  
One of the tasks of molecular photonics is the development of electroluminescent devices for emitting information panels, optoelectronic devices, etc. A possible polymeric material for solving this problem can be both photoactive, electrically conductive matrices and polymeric ligands. In addition, an important approach is the use of thin electroluminescent polymer layers instead of materials based on low molecular weight phosphors. The advantage of this approach is the rejection of energy-consuming vacuum deposition of phosphors in favor of solution technologies compatible with the deposition of coatings in a centrifugal field and with the use of inkjet, screen, and matrix printing technologies for optoelectronic circuits [1, 2]. In the arsenal of polymer physics and chemistry, there are several ways to create new materials for use in electroluminescent devices. These include, first, the synthesis of highly efficient electroluminescent homo- and copolymers [3, 4]; secondly, the creation of composite materials (for example, the dispersion of luminescent quantum dots in a conductive polymer matrix) [5, 6, 7, 8]. In addition, the design of organo\(-\)inorganic hybrid photo- and electroluminescent materials, for example, based on metal\(-\)polymer complexes (MPCs), is also an interesting direction [9, 10, 11, 12, 13]. In the latter case, lanthanide ions Ln\({}^{3+}\) are often used as the luminescent component, which is due to the special structure of the outer electronic levels of three-charged rare-earth ions: the energies of these levels are well separated due to screening of 4f-orbitals by electrons of 5s- and 5p-sublevels; intra-level transitions 4f-4f, covering the region of visible and near infrared radiation, are clear and well recognized as well. Thus, the luminescence of Ln\({}^{3+}\) ions is characterized by quasi-monochromatic emission (the half-width of the luminescence bands is 5-10 nm, while for organic chromophores it is up to 100 nm), the stability of emission over time, the independence of the position of the luminescence bandsfrom the nature of the ligand and solvent, and a large pseudo-Stokes shift in complexes, as well as a long lifetime of the excited state (\(\approx\)1000 \(\upmu\)s) [14; 15]. The main problem is the selection and synthesis of a polymeric ligand capable of providing efficient intramolecular transfer of electronic excitation energy to the central Ln\({}^{3+}\) atom. Units not participating in complexation should provide the desired optical and electrically conductive properties. To develop a polymer ligand with unique properties, we chose promising monomers, namely \(N\)-vinylcarbazole (VK) and 1-vinyl-1,2,4-triazole (VT), for the synthesis of new effective copolymers. This choice was because the synthetic features, physicochemical, and optical properties of homopolymers based on VK and VT have been thoroughly studied, widely presented in scientific publications, and testify to their originality. It has been established that poly(\(N\)-vinylcarbazole) (PVK) is characterized by mechanical strength, high chemical and thermal stability, and has a predominantly \(p\)-type electrical conductivity [16]. PVK exhibits a high photoelectric sensitivity in the UV region of the spectrum, which increases significantly upon sensitization of the polymer with various dopants (di-, tri-, and tetranitro-9-fluorenone; \(p\)-chloranil; and \(p\)-bromanil), while the maximum of the spectral dependence of the photosensitivity shifts to the visible region of the spectrum [17; 18; 19]. On the basis of PVK, effective electrophotographic layers have been developed that are used to develop information carriers. PVK is promising for the development of photosensitive layers of solar cells, organic light-emitting diodes (OLED), and organic field effect transistors (OFET) [20; 21].