Preparation And Luminescent Properties Of Red Fluorescent Phosphors For Solid State Lighting

With the aggravation of energy crisis and environmental pollution worldwide, the research and development of novel materials in the consideration of renewable energy and energy conservation and emission reduction free of pollution has become a contemporary theme of social development. As a new generation of the green lighting source, Light-emitting diodes(LEDs) have attracted great attentions and possess widespread application prospects due to its outstanding properties. However, As the most common way to generate white light on the market, the application of LED blue chip loaded with a yellow phosphor in the field of general lighting is limited to its insufficient red light, low color rendering index and high color temperature.With the development of semiconductor lighting technology, the application of LED lighting technology in modern agriculture has also been widely concerned.In particular, red emitting devices is critical to photosynthesis and plant growth.Based on the requirements of red emitting phosphor and devices,this thesis investigated the relation between structure and luminescent properties of rare erth ion doped red fluorescent materials in sulfide system, phosphate system and gallate system, discuss application in both general lighting and LED plant lighting. The achievements that have been made are summarized as follows:A. Red emission phosphor of Ca S:Eu2+ was sucessfully prepared. The effect of different firing temperature and flux content on the morphology, particle size distribution and luminescence properties was approached.The 653 nm red emission under the 476 nm blue light was achieved potentially useful in the white LEDs, enabling an improvement of the color rendering index and color temperature of the device. Meanwhile, this red emission band matches well with red light absorption band of plant photosynthesis, exhibiting a potential application in the field of plant illumination.B. The Ca3(PO4)2:Eu2+, Mn2+ phosphor exhibits synchronous 660 nm red and 420 nm blue emission. The enhancement of Eu2+ sensitizer on the Ca3(PO4)2:Mn2+ red phosphor and energy transfer mechanism between Eu2+ and Mn2+ were revealed. The luminescent spectrums match well with absorption of photosynthesis pigments in plant, indicating its potential application in the field of plant illumination. A prototype of plant-LEDs was fabricated with 365 nm UV LED chip and as-prepeared phosphor.C. The Cr3+ doped Zn Ga2O4 red phosphor was prepared and the effect of Al3+ substitutes Ga3+ and Mg2+ substitutes Zn2+ on the structure and luminescence properties was clarified in terms of the relationship between Cr3+ ion 3d electron transition and matrix crystal field splitting.