Tb3+ ion green emissions by the energy transfer from ZnO nanocrystals embedded in SiO2 film

• Main Author: Tang, Dennis Khean Kee
• Other Authors: Kantisara Pita
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
• Online Access: http://hdl.handle.net/10356/74679
• Institution: Nanyang Technological University

The direct wide band gap of 3.37eV of Zinc Oxide (ZnO) makes it a material that can be used in electronics and optoelectronic devices. Energy transfer from Zinc Oxide nanocrystals (ZnO-nc) embedded in Silicon dioxide (SiO2) matrix has been proven to be able to excite Rare earth (RE) ions like Europium (Eu3+) and Terbium (Tb3+) to produce visible lights of different colours. In this project, the method that can produce the highest efficiency in energy transfer between Zinc oxide nanocrystals and Terbium ions embedded in Silicon dioxide matrix prepared using the Sol-gel technique will be investigated. The emission of ZnO-nc embedded in SiO2 matrix are affected by three factors, concentration of ZnO in the mixture, annealing temperature to form ZnO crystals, and the atmospheric environment when annealing the samples. The excitation spectra of Terbium and the emission spectral for all the samples are examined to show the energy transfer from Zinc oxide nanocrystals to Terbium. This report shows how the annealing temperature and concentration level of Zinc oxide in the mixture affects the emission in the UV region, which is used to excite the Tb3+ ions for green emission. The current optimum fabrication process for maximum green emission at 545nm from the sample is shown in this report, where annealing the sample with 12mol% of Tb3+, using the formula [(Moles of Tb / Moles of (Tb+Zn+Si)) x 100%], added to Zinc concentration of 40%, using the formula [( Moles of Zn Moles of (Zn+Si)) x 100%], and annealed at 400˚c is shown to have the highest emission. This study will be able to aid in the creation of a low cost and high efficiency light emitting diode (LED).