Si-N Structure And Photoluminescence Of Oxonitridosilicate Phosphor And Its Semiconductor Based Light-Emitting Diodes

In white-light-emitting diodes (WLEDs) technology, ultraviolet or blue InGaN chip/phosphor-converted regime is a mainstream strategy to generate white-light. Therefore, blue-light excitable, thermally and chemically stable phosphors like oxonitridosilicate sereies have become much concerned worldwide.Focused on such kinds of phosphors with Si-N bond, the effect of Si-N on emission properties for oxonitridosilicate and oxosilicate luminescent materials by ionic co-doping and partial nitridizing methods was investigated. The main achievements made in this work include:A. Photoluminescence (PL) intensity of SrSi₂O₂N₂:Eu²⁺ has been enhanced by co-doping Mn²⁺, Mg²⁺ and Al3+, resulting in an intensified photoluminescence at a maximum by 355%, 28% and 42%, respectively. The route of energy transfer to Mn for SrSi₂O₂N₂:Mn²⁺,Eu²⁺ was proposed to be in a three-path regime, one is from SrSi₂O₂N₂ host, the second from Eu²⁺ and the third from incident photon directly, eventually results in an increase of the PL intensity of Mn.B. For Ba₃MgSi₂O₈:Eu²⁺,Mn²⁺, an attempt was made by incorporating Si-N to intentionally promote the formation of green-light-emitting Ba2SiO4 phase to produce white-light. As the N and Li-added amount changes, the amount of the two phases in the mixed phases and energy transfer of Eu-Mn on sites in different hosts of phases are adjusted, consequently resulting in a full-color band emission.C. For Sr2MgSi2O7:Eu²⁺, the effect of Si-N incorporation on the structure of host and resultant enhancement of photoluminescence were investigated. As the amount of nitrogen varied from 0 to 0.6(at.), the luminescent intensity is found to be increased by 69%. As a result, with incorporation of nitrogen in small amount, the luminous intensity, chromaticity coordinates and the color purity as well can be adjusted to a desired value.D. For Sr₂Si₅N₈ with Si-N bond, a carbon thermal reduction route was explored. The analysis results showed that there are SrSi₂O₂N₂, Sr₂Si₅N₈ and other phases, in which the main phase is SrSi₂O₂N₂. Two dominant factors closely associated with the formation of desired phase are reducing gas and heating rate.E. White LED devices were fabricated with commercial InGaN chip and self-made SrSi₂O₂N₂:Mn²⁺,Eu²⁺ phosphor in our laboratory. The color rendering index of 93.3% and the correlated color temperature of 3584K are achieved.