To obtain luminescent lanthanide complexes with a low energy LMCT state the 2-(2′-mercaptophenyl)benzothiazolates, Ln(SSN)₃, and 2-(2′-mercaptophenyl)benzoxazolates, Ln₂(OSN)₆ (Ln = Gd, Yb), were synthesized by the reaction of amides Ln[N(SiMe₃)₂]₃ with respective thiophenols. Ytterbium complexes were structurally characterized by X-ray diffraction analysis. Cyclic voltammetry revealed that the deprotonated mercaptophenyl ligands have significantly lower oxidation potentials than their phenoxy analogues and some β-diketones. The photophysical properties of Gd and Yb compounds were studied both in solution and in the solid state. The fluorescence spectra of the compounds in solution display the bands of the keto and enol forms of the ligands. No energy transfer from the organic part to Yb³⁺ has been detected in solutions of both Yb complexes, whereas in solids an intense metal-centered emission in the near infrared region was observed. The solid Gd compounds exhibited room temperature phosphorescence caused by unusually efficient intersystem crossing facilitated by the essentially reducing properties of OSN and SSN ligands. To explain the sensitization process occurring in solids Yb₂(OSN)₆ and Yb(SSN)₃ a specific non-resonant energy transfer mechanism via a ligand to metal charge transfer state has been proposed. Based on the Yb derivatives, NIR-emitting OLEDs with 860 μW cm⁻² maximal irradiance were obtained. Their Gd counterparts showed bright electrophosphorescence (up to 1350 cd m⁻²) in the devices containing doped emission layers.

Optimum conditions for the growth of the GaAs_{1 − x} Sb _x /GaAs heterostructures by the method of molecular-bean epitaxy are determined; it is shown that effective long-wavelength photoluminescence at T = 300 K can be obtained at wavelengths as long as λ = 1.3 μm by increasing the antimony incorporation. As the excitation power is increased, the appearance of a short-wavelength line (in addition to a shift of a photoluminescence maximum to shorter wavelengths characteristic of the type II heterojunctions) related to direct optical transitions in the real space takes place; this relation is confirmed by the results of studying the photoluminescence spectra with subpicosecond and nanosecond time resolution in the case of pulsed excitation.