Fabrication, Patterning, and Optical Properties of Nanocrystalline YVO4:A (A = Eu3+, Dy3+, Sm3+, Er3+) Phosphor Films via Sol−Gel Soft Lithography

• Published in: Chemistry of materials 2002-05, Vol.14 (5), p.2224-2231
• Main Authors: Yu, M, Lin, J, Wang, Z, Fu, J, Wang, S, Zhang, H. J, Han, Y. C
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Materials science; Microelectronic fabrication (materials and surfaces technology); Nanocrystals and nanoparticles; Nanoscale materials and structures: fabrication and characterization; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm011663y

Nanocrystalline YVO4:A (A = Eu3+, Dy3+, Sm3+, Er3+) phosphor films and their patterning were fabricated by a Pechini sol−gel process combined with soft lithography. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), atomic force microscopy (AFM) and optical microscopy, UV/vis transmission and absorption spectra, photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 400 °C and the crystallinity increased with the increase of annealing temperatures. Transparent nonpatterned phosphor films were uniform and crack-free, which mainly consisted of grains with an average size of 90 nm. Patterned gel and crystalline phosphor film bands with different widths (5−60 μm) were obtained. Significant shrinkage and a few defects were observed in the patterned films during the heat treatment process. The doped rare earth ions (A) showed their characteristic emission in crystalline YVO4 phosphor films because of an efficient energy transfer from vanadate groups to them. The Sm3+ and Er3+ ions also showed upconversion luminescence in a YVO4 film host. Both the lifetimes and PL intensity of the rare earth ions increased with increasing annealing temperature from 400 to 800 °C, and the optimum concentration for Eu3+ was determined to be 7 mol % and those for Dy3+, Sm3+, and Er3+ were 2 mol % of Y3+ in YVO4 films, respectively.