Tuning of emission bands of phosphors and quantum dots, and their applications to white light sources, and understanding of electronic structure via quantum calculation = 형광체와 양자점의 발광 파장 제어 및 백색 광원으로의 응용과 양자 계산을 통한 에너지 준위 분석

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In this thesis, emission control of phosphors and quantum dots (QDs) is reported to achieve excellent white light sources and new yellow-emitting phosphors for white light-emitting diodes (LEDs) are introduced. And the combination of phosphor with semiconductor QDs is firstly tried for the generation of white light. In addition, this thesis shows that quantum calculation using density functional theory (DFT) is useful for the analyses of electronic structure of phosphors and the design of new phosphors. And it is shown that yellow-emitting phosphors in this study can be applied to white light sources using various primary sources [e.g., carbon nanotubes (CNTs)] as well as white light sources using LEDs. In chap. 3, widely used yellow-emitting $Y_3Al_5O_{12}:Ce^{3+}$ (YAG:Ce)-based phosphors are discussed. Yellow-emitting $Y_{2.94-x}Al_5O_{12}:Ce^{3+}_{0.06}$, $Pr^{3+}_x$ (YAG:Ce,Pr) phosphors where x = 0, 0.006, 0.015, 0.03, and 0.06 were synthesized to enhance red spectral intensity and YAG:Ce,Pr is reported in section 3.1. Sharp red emission peaking at about 610 nm was observed from $Y_3Al_5O_{12}:Ce^{3+}$, $Pr^{3+}$ (YAG:Ce,Pr) and it is ascribed to the transition of $^1D_2$ → $^3H_4$ of $Pr^{3+}$. Although red emission peak was observed in YAG:Ce,Pr, yellow emission intensity decreased as the amount of $Pr^{3+}$ was increased. To investigate the origin of the decrease of yellow emission via the electronic transition of $5d^1$ → 4f of $Ce^{3+}$, crystal structure, particle size, and energy transfer were considered. It is suggested that the decrease of yellow emission is attributed to the radiative or non-radiative energy transfer from $Ce^{3+}$ to $Pr^{3+}$. In the case of non-radiative energy transfer, energy transfer occurred from $Ce^{3+}$ to $Pr^{3+}$ via dipole-dipole interaction and calculated critical distance for the energy transfer was 12$\textrm{\AA}$. In Section 3.2, $Tb^{3+}$ -substituted YAG:Ce [(Y, Tb)AG:Ce] is dealt with. Yellow-emit...
Jeon, Duk-Youngresearcher전덕영researcher
한국과학기술원 : 신소재공학과,
Issue Date
303614/325007  / 020055131

학위논문(박사) - 한국과학기술원 : 신소재공학과, 2008. 8., [ xxiii, 304 p. ]


phosphor; quantum dots; light-emitting diodes; luminescence; white light source; 형광체; 양자점; 발광 다이오드; 발광; 백색광원

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