Aleksandr Fedorov

This work presents a comprehensive study of the structural, luminescent, and photoconversion properties of epitaxial composite phosphor converters based on single crystalline films of Ce³⁺-activated Ca_2−xY_1+xMg_1+xSc_1−xSi₃O₁₂:Ce (x = 0–0.25) (CYMSSG:Ce) garnet, grown using the liquid phase epitaxy (LPE) method on single-crystal Y₃Al₅O₁₂ (YAG) and YAG:Ce substrates. The main goal of this study is to elucidate the structure–composition–property relationships that influence the photoluminescence and photoconversion efficiency of these film–substrate composite converters, aiming to optimize their performance in high-power white light-emitting diode (WLED) applications. Systematic variation in the Y³⁺/Sc³⁺/Mg²⁺ cationic ratios within the garnet structure, combined with the controlled tuning of film thickness (ranging from 19 to 67 µm for CYMSSG:Ce/YAG and 10–22 µm for CYMSSG:Ce/YAG:Ce structures), enabled the precise modulation of their photoconversion properties. Prototypes of phosphor-converted WLEDs (pc-WLEDs) were developed based on these epitaxial structures to assess their performance and investigate how the content and thickness of SCFs affect the colorimetric properties of SCFs and composite converters. Clear trends were observed in the Ce³⁺ emission peak position, intensity, and color rendering, induced by the Y³⁺/Sc³⁺/Mg²⁺ cation substitution in the film converter, film thickness, and activator concentrations in the substrate and film. These results may be useful for the design of epitaxial phosphor converters with tunable emission spectra based on the epitaxially grown structures of garnet compounds.

This study investigates the structural, luminescent, and photoconversion properties of composite converters based on epitaxial structures containing single-crystalline films of Ce³⁺-doped Ca₂₋ₓY₁₊ₓMg₁₊ₓSc₁₋ₓSi₃O₁₂:Ce (x=0–0.25) (CYMSSG:Ce) garnet, and Y₃Al₅O₁₂ (YAG) or YAG:Ce substrates, grown using the Liquid Phase Epitaxial (LPE) method. The research focuses on a detailed analysis of the properties of film-crystal composite converters to achieve a deeper understanding of their photoconversion performance, providing an innovative approach to designing a new type of film/ substrate converters for white LEDs. This was accomplished by systematically varying the Y/Sc/Mg cation content in the film and adjusting the film thickness within the range of 19–67 µm for CYMSSG:Ce/YAG structures and 10–22 µm for CYMSSG:Ce/YAG:Ce structures. A significant emphasis of this research was placed on mapping the performance of these converters using a color coordinate diagram, a key tool for visualizing the relationship between film composition, thickness, and photoconversion efficiency. The resulting data revealed clear and distinct trends, offering valuable insights into the tunability of the luminescent properties of white LEDs through precise control of content and film thickness.