Structural and Luminescent Properties of Multi-functional Rare-earth Doped Phosphors

• Main Authors: Tzu-Chen Liu, 劉子晨
• Other Authors: 劉如熹
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/21693165927719900386

博士 === 國立臺灣大學 === 化學研究所 === 100 === The applications of phosphors according to different excitation sources are versatile due to the utilization of rare earth ions. The tunable energy levels of 5d orbital and the large number of energy levels of 4f orbitals can emit photons with different wavelength. In this thesis, excitation sources from vacuum ultraviolet (VUV), ultraviolet (UV) to visible photons, and electrons are investigated. Emission ranges from UV to visible range and near-infrared (NIR) are also utilized. The third chapter focuses on the synthesis of red-emitting oxynitride phosphor. Intraconfigurational 4f → 4f transitions are designed because of the determined environment for 5d → 4f transitions. The high thermal stability reveals that β–SiAlON is a good candidate for white light-emitting diodes (wLEDs) and plasma display panels (PDP). Pr3+ ions show the possibility of an alternative for red emitting activators. In the fourth chapter, comparison of LED- and FED-used phosphors under electron bombardment is made and it suggests a new class of host lattice should be developed. Evidences from solid-state nuclear magnetic resonance (ssNMR) lead to a different explanation of the incorporation of rare-earth ions into AlN host lattice. A new phosphor composition of AlN doped with Si4+ and Ce3+ ions is synthesized and shows the validity for field emission displays. The fifth chapter includes two proposed quantum cutting (QC) rare-earth combination for enhancing the efficiency of crystalline silicon (c-Si)-based solar cells: (1) adding a sensitizer to transfer the excited energy to the donor with 4f → 4f transitions , and (2) using a broad band donor such as Eu2+ and Ce3+ ions. It is concluded that due to the high energy of phonons required for Ce3+ ions, Eu2+-Yb3+ pairs is a better choice.