에너지-전이 형광 특성 향상을 위한 다공성 실리카 중간층이 추가된 코어-쉘 나노입자 제조 및 특성평가

심우형,김세윤,신원호,정형모 대한금속·재료학회 2020 대한금속·재료학회지 Vol.58 No.2

Multi-layer core-shell nanoparticles (YVO4:Nd3+/mSiO2/SiO2) consisting of silica cores (SiO2), mesoporous silica (mSiO2) intermediate layers, and Neodymium doped rare-earth phosphor (YVO4:Nd3+) shell layers were successfully synthesized using the stepwise sol-gel method. The morphological structure and optical properties of the functional core-shell nanoparticles were characterized and evaluated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) analysis. mSiO2 intermediate layers were utilized as the bridge between the core and shell materials. Their porous surfaces served to anchor the YVO4:Nd3+ crystals. This prevents energy loss during the energy transfer of electrons, resulting in improved optical properties. The use of intermediate layer combinations of mSiO2/SiO2 in the coreshell structure also improved cost-effectiveness, because the core is filled with cheap silica, not expensive phosphors. Even though the nanoparticles used only a thin layer of the photoluminescent shell materials, the optical properties, resulting from the energy-transfer emitting mid-infrared light, were remarkably enhanced by increasing the crystallinity of the phosphor. To demonstrate the practical use of the synthesis method, the photoluminescent properties of the core-shell nanoparticles were optimized by adjusting the annealing temperature and scaling to mass production. We believe that our efficient synthetic strategy provides a facile way of obtaining functional, cost-effective core-shell nanoparticles with improved photoluminescent properties.

Facile Synthesis, Characterization, Nanocrystal Growth and Photoluminescence Properties of GeS Nanowires

Zhiqiang Lai,YAN-JIE GUO,Peihui Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.12

As a IV–VI semiconductor, GeS is winning wide attention for its excellent properties. However, few examples of GeS nanostructures, especially those with photoluminescence (PL) properties, have been reported. After the optimization of reaction conditions, including time and temperature, the GeS nanowires with PL properties are synthesized via a green, facile hydrothermal route without using any toxic reagent. These materials are characterized by transmission and scanning electron microscopy (TEM and SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), etc. With the average diameter of ~200 nm and the length ranging from 1–25 µm, the resulting GeS nanowires have relatively smooth surface and round top, and are oriented along [100] facet. The growth mechanism of GeS nanowires is investigated, and the understanding of their growth mechanism could provide helpful guidance for designing experimental conditions rationally to synthesize nanowires. Due to their special nanostructure, these nanowires possess very good fluorescent properties, which indicates that these nanowires have potential to apply in future optical nanodevices.

Photophysical and Thermal Properties of Polyazomethines Containing Various Flexible Units

İsmet Kaya,Ali Avcı,Kevser Temizkan 한국고분자학회 2017 Macromolecular Research Vol.25 No.1

In this study, the poly(azomethine-ether-urethane), poly(azomethine-ester) and poly(azomethine-epoxyether) compounds were prepared to investigate effect of various flexible units on some physical properties like thermal stability and photophysical properties. Structural characterizations were made by FTIR, 1H NMR, 13C NMR, and UV-Vis analyses. The molecular weight distributions of polymers were performed by gel permeation chromatography (GPC) measurement. The chemical and physical properties of polymers were examined by thermogravimetry (TG), differential scanning calorimetry (DSC), photoluminescence (PL), dynamic mechanical analysis (DMA), scanning electron microscope (SEM) and atomic force microscopy (AFM) techniques. As a result, the outstanding properties related to the photoluminescence and thermal measurements of the polymers were obtained. Therefore, the presented photoluminescent polymers could be used in thermally stable photo-functional materials.

Photoluminescence properties of a novel green-emitting phosphor Zr_1−<i>x</i>O₂:<i>x</i>Tb³⁺

Yoon, S.J.,Park, K. Elsevier 2015 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.40 No.1

<P><B>Abstract</B></P> <P>In this study, a series of Zr<SUB>1−<I>x</I> </SUB>O<SUB>2</SUB>:<I>x</I>Tb<SUP>3+</SUP> (0.03 ≤ <I>x</I> ≤ 0.13) nanopowders was prepared by the solution combustion method. The microstructure and photoluminescence properties of the Zr<SUB>1−<I>x</I> </SUB>O<SUB>2</SUB>:<I>x</I>Tb<SUP>3+</SUP> phosphors were studied in accordance with the Tb<SUP>3+</SUP> content and annealing temperature. The Zr<SUB>1−<I>x</I> </SUB>O<SUB>2</SUB>:<I>x</I>Tb<SUP>3+</SUP> phosphors crystallized in a tetragonal structure. The emission spectra of the Zr<SUB>1−<I>x</I> </SUB>O<SUB>2</SUB>:<I>x</I>Tb<SUP>3+</SUP> phosphors under 296 nm excitation showed strong emission peaks at 489, 545, 587, and 617 nm, which were attributed to the <SUP>5</SUP>D<SUB>4</SUB> → <SUP>7</SUP>F<SUB>6</SUB>, <SUP>5</SUP>D<SUB>4</SUB> → <SUP>7</SUP>F<SUB>5</SUB>, <SUP>5</SUP>D<SUB>4</SUB> → <SUP>7</SUP>F<SUB>4</SUB>, and <SUP>5</SUP>D<SUB>4</SUB> → <SUP>7</SUP>F<SUB>3</SUB> transitions of Tb<SUP>3+</SUP> ions, respectively. The Zr<SUB>0.95</SUB>O<SUB>2</SUB>:0.05Tb<SUP>3+</SUP> phosphor showed the most efficient emission properties. In addition, the emission intensity of the Zr<SUB>0.95</SUB>O<SUB>2</SUB>:0.05Tb<SUP>3+</SUP> phosphor was enhanced with an increase in the annealing temperature up to 900 °C due to the improved crystallinity and reduced crystal defects in the powders. The optimal Tb<SUP>3+</SUP> content and annealing temperature for the Zr<SUB>1−<I>x</I> </SUB>O<SUB>2</SUB>:<I>x</I>Tb<SUP>3+</SUP> phosphors were determined to be 0.05 and 900 °C, respectively. Zr<SUB>1−<I>x</I> </SUB>O<SUB>2</SUB>:<I>x</I>Tb<SUP>3+</SUP> showed great potential as a green-emitting phosphor for white light-emitting diodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zr<SUB>1−<I>x</I> </SUB>O<SUB>2</SUB>:<I>x</I>Tb<SUP>3+</SUP> phosphors crystallize in the tetragonal structure. </LI> <LI> Optimal Tb<SUP>3+</SUP> content and annealing temperature are 0.05 and 900 °C, respectively. </LI> <LI> Zr<SUB>1−<I>x</I> </SUB>O<SUB>2</SUB>:<I>x</I>Tb<SUP>3+</SUP> shows great potential as a green-emitting phosphor for white LEDs. </LI> </UL> </P>

PECVD 방법으로 증착한 SiOx(x<2) 박막의 광학적 특성 규명

김영일 ( Young Ill Kim ),박병열 ( Byoung Youl Park ),김은겸 ( Eun Kyeom Kim ),한문섭 ( Mun Sup Han ),석중현 ( Jung Hyun Sok ),박경완 ( Kyoung Wan Park ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.9

Silicon oxide thin films were deposited by using a plasma-enhanced chemical-vapor deposition technique to investigate the light emission properties. The photoluminescence characteristics were divided into two categories along the relative ratio of the flow rates of SiH4 and N2O source gases, which show light emission in the broad/visible range and a light emission peak at 380 nm. We attribute the broad/visible light emission and the light emission peak to the quantum confinement effect of nanocrystalline silicon and the Si=O defects, respectively. Changes in the photoluminescence spectra were observed after the post-annealing processes. The photoluminescence spectra of the broad light emission in the visible range shifted to the long wavelength and were saturated above an annealing temperature of 900℃ or after 1 hour annealing at 970℃. However, the position of the light emission peak at 380 nm did not change at all after the post-annealing processes. The light emission intensities at 380 nm initially increased, and decreased at annealing temperatures above 700℃ or after 1 hour annealing at 700℃. The photoluminescence behaviors after the annealing processes can be explained bythe size change of the nanocrystalline silicon and the density change of Si=O defect in the films, respectively. These results support the possibility of using a silicon-based light source for Si-optoelectronic integrated circuits and/or display devices.

Room-temperature photoluminescence behavior of α-V₂O₅ and mixed α-β phase V₂O₅ films grown by electrodeposition

Le, Top Khac,Kang, Manil,Kim, Sok Won Elsevier 2019 Materials science in semiconductor processing Vol.94 No.-

<P><B>Abstract</B></P> <P>Vanadium pentoxide (V<SUB>2</SUB>O<SUB>5</SUB>) films with micro-nanostructure were fabricated by an electrodeposition method using an aqueous solution of NH<SUB>4</SUB>VO<SUB>3</SUB>. The surface morphology and structural properties of the V<SUB>2</SUB>O<SUB>5</SUB> were investigated by SEM and XRD measurements. The results show that the annealing temperature strongly affects the surface morphology, crystal structure, and photoluminescence (PL) properties. The formation of α-V<SUB>2</SUB>O<SUB>5</SUB> structure occurred when the sample was annealed at temperatures below 500 ℃. As the annealing temperature increases, some of the α-V<SUB>2</SUB>O<SUB>5</SUB> structures were distorted and restructured to form a high-quality mix of α-β phase V<SUB>2</SUB>O<SUB>5</SUB>. This leads to great enhancement of the PL due to the presence of numerous defects on the surface of the V<SUB>2</SUB>O<SUB>5</SUB> films. Moreover, the mixing of the α-β phase V<SUB>2</SUB>O<SUB>5</SUB> leads to wide absorption and enhancement of the visible-light emission from V<SUB>2</SUB>O<SUB>5</SUB> micro-nanostructure.</P>

Germanosilicate glasses containing PbSe quantum dots for mid-infrared luminescence

Wang, J.,Zhang, J.,Liu, C.,Heo, J.,Kwon, Y.K. North-Holland 2016 Journal of non-crystalline solids Vol.431 No.-

<P>Lead selenide quantum dots (QDs) were precipitated in germanosilicate glasses to investigate the effect of GeO2 content on the precipitation and optical properties. The absorption and photoluminescence (PL) bands red-shifted strongly as GeO2 concentration increased. After heat-treatment at 470 degrees C for 10 h, the first excitonic absorption bands red-shifted from 801 nm to 2593 nm as GeO2 content increased from 0 to 40 mol%, and thus PL at 2619 nm was achieved. The corresponding average QD diameters were 2.48-12.54 nm. The precipitation of large PbSe QDs resulted from the enhancement of diffusion with the increase of GeO2 concentration, and is the main reason for these red-shifts. (C) 2015 Elsevier B.V. All rights reserved.</P>

Effect of Reaction Time on Optical Properties of CsPbBr₃ Perovskite Nanocrystals

Sung Hun Kim,Yong-Ryun Jo,Yong Bin Kim,Ju Seok Kim,Sang-Youp Yim,Hong Seok Lee 한국진공학회(ASCT) 2021 Applied Science and Convergence Technology Vol.30 No.5

We have studied the optical and structural properties of CsPbBr₃ perovskite nanocrystals (NCs) fabricated with various reaction times. The temporal evolution of the ensemble optical properties, such as absorption and fluorescence (FL) spectra and photoluminescence quantum yield (PLQY), was recorded under a set reaction temperature (170 ℃) and various amounts of time (5 s – 60 min). The FL intensity of the CsPbBr₃ NCs gradually decreased with increasing reaction time, and the observed PLQY of the CsPbBr₃ NCs ranged from less than 20% up to 35% because of the enlarged crystal size and the induced charge trap states. The FL peaks of as-obtained CsPbBr₃ NCs were tuned in the range of 516.8 to 526.8 nm with increasing reaction time as a result of the ripening phenomenon. Transmission electron microscopy and selected area electron diffraction analysis were performed to analyze the structural properties. The results revealed that the average edge length of CsPbBr₃ NCs with a reaction time of 5 s was 13.4 nm and confirmed that the cubic crystal structure was well ordered.

Photoluminescence properties of Eu 2+ ‐activated thiogallate phosphors

조영식,복문수,허영덕 대한화학회 2024 Bulletin of the Korean Chemical Society Vol.45 No.2

This work analyzes the crystal structural properties and photoluminescence properties of six Eu 2+ ‐activated thiogallates: CaGa 2 S 4 :Eu 2+ , SrGa 2 S 4 :Eu 2+ , EuGa 2 S 4 , BaGa 2 S 4 :Eu 2+ , Sr 2 Ga 2 S 5 :Eu 2+ , and Eu 2 Ga 2 S 5 . Photoluminescence parameters such as the absorption energy ( E abs ), emission energy ( E em ), zero‐phonon line energy ( E 0 ), Stokes shift (Δ S ), and red shift ( D ) are discussed. This work is the first report on the photoluminescence parameters of these six Eu 2+ ‐activated thiogallates and therefore provides important information about these materials. This work analyzes the crystal structural properties and photoluminescence properties of six Eu2+-activated thiogallates: CaGa2S4:Eu2+, SrGa2S4:Eu2+, EuGa2S4, BaGa2S4:Eu2+, Sr2 Ga2S5:Eu2+, and Eu2 Ga2S5. Photoluminescence parameters such as the absorption energy (Eabs), emission energy (Eem), zerophonon line energy (E0), Stokes shift (ΔS), and red shift (D) are discussed. This work is the first report on the photoluminescence parameters of these six Eu2+-activated thiogallates and therefore provides important information about these materials.

Synthesis, Complexation and Fluorescence Properties of N-Anthracenylmethyl Dipodal Ligand with Quinoline End-Group

Youngjin Kang,Seok-Tae Moon,박선홍,Jinho Kim,이심성,박기민 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.5