• 한국세라믹학회지
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• 제40권10호
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• pp.949-953
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• 2003

청색 발광특성을 갖는 CaWO$_4$ 형광체를 rf 마그네트론 스퍼터링 방법으로 박막화를 시도하고,증착변수와 열처리 조건이 발광특성에 미치는 영향을 관찰하였다. 증착조건인 산소/아르곤 가스비, 기판온도에 따라서 박막의 구조적, 화학양론적 물성이 크게 영향을 받고 있었다. 후 열처리 공정에 의하여 발광특성의 향상을 얻을 수 있었다. 산소공공에 의한 청록색 영역의 발광도 관찰되었으며, 박막내의 산소결함이 제어되면서 청색 발광스펙트럼을 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제26권2호
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• pp.201-214
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• 2005

We have designed and developed novel luminescent lanthanide complexes for advanced photonics applications. Lanthanide(III) ions (Ln$^{3+}$) were encapsulated by the luminescent ligands such as metalloporphyrins and naphthalenes. The energy levels of the luminescent ligands were tailored to maintain the effective energy transfer process from luminescent ligands to Ln$^{3+}$ ions for getting a higher optical amplification gain. Also, key parameters for emission enhancement and efficient energy transfer pathways for the sensitization of Ln$^{3+}$ ions by luminescent ligands were investigated. Furthermore, to enhance the optophysical properties of novel luminescent Ln$^{3+}$ complexes, aryl ether-functionalized dendrons as photon antennas have been incorporated into luminescent Ln$^{3+}$ complexes, yielding novel Ln(III)-cored dendrimer complex. The novel Ln(III)-cored dendrimer complex has much higher PL intensity than the corresponding simple complex, due to the efficient site-isolation effect. In this article, we will deal with recent progress in the synthesis and photophysical studies of inert and stable luminescent Ln$^{3+}$ complexes for advanced photonics applications. Also, our review will include the exploratory investigation of the key parameters for emission enhancement and the effective energy transfer pathways from luminescent ligands to Ln$^{3+}$ ions with Ln(III)-chelated prototype complexes.

• 한국재료학회지
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• 제16권1호
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• pp.58-62
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• 2006

Effects of doping concentration and annealing atmosphere on the luminescent properties of $Er^{3+}$ doped ZnO phosphor powders were investigated. Photoluminescence (PL) spectra of ZnO:Er exhibit an orange emission band at around 575 nm, while those of pure ZnO show a green emission at 520 nm. Emission difference between ZnO:Er and pure ZnO is attributed to the energy transfer of Er ions in ZnO. The highest PL intensity is obtained by doping 1 mol% Er to ZnO. Luminescent properties of ZnO:Er phosphors annealed at $N_2$+vacuum atmosphere are superior to those annealed at $N_2$ atmosphere.

• Bulletin of the Korean Chemical Society
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• 제25권3호
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• pp.343-344
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• 2004

• 한국세라믹학회지
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• 제28권3호
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• pp.252-258
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• 1991

Spectral properties of europium activated intermediate compounds in the system R2O3-P2O5(R=La, Y, and Gd) are presented, including also phosphors with bismuth and vanadate sensitization. The sensitized phosphors are less efficient than unsensitized phosphors. (The ratio of oxygen to phosphorus effects the charge transfer band) Most phosphors have low efficiencies, but La3PO7 and Gd3PO7 hosts are possible for commercial luminescent materials.

• 한국분말재료학회지
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• 제25권2호
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• pp.170-177
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• 2018

Colloidally synthesized luminescent nanocrystals (NCs) have attracted tremendous attention due to their unique nanoscale optical and electronic properties. The emission properties of these NCs can be precisely tuned by controlling their size, shape, and composition as well as by introducing appropriate dopant impurities. Nowadays, these NCs are actively utilized for various applications such as optoelectronic devices including light emitting diodes (LEDs), lasers, and solar cells, and bio-medical applications such as imaging agents and bio-sensors. In this review, we classify luminescent nanomaterials into quantum dots (QDs), upconversion nanoparticles (UCNPs), and perovskite NCs and present their intrinsic emission mechanism. Furthermore, the recently emerging issues of efficiency, toxicity, and durability in these materials are discussed for better understanding of industry demands. As well, the future outlook will be offered for researchers to guide the direction of future research.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.52-55
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• 2009

A red phosphor, $(Sr,Ca)_2P_2O_7:Eu^{2+},Mn^{2+}$, for UV-LED was synthesized under a reducing atmosphere, and its luminescent properties were investigated. The phosphor absorbs ultraviolet light at around 400 nm and efficiently emits red light at approximately 610 nm through an energy transfer from $Eu^{2+}$ to $Mn^{2+}$. Using the varied input current test for the phosphor-loaded LED lamps, it was found that the luminescent efficiency of the phosphor decreased with increasing light flux. This might be due to an increased probability of excited-state absorption and the consequent non-radiative relaxation in $Mn^{2+}$ ions in the condition of high photon influx.

• 한국재료학회지
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• 제15권6호
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• pp.419-425
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• 2005

In this paper, we describe the luminescent properties of the phosphors synthesized via sol-gel technique. When the phosphor prepared by sol-gel technique, reaction factors, such as pH condition, $R_w$ and drying temperature affected the luminescent intensity, particle size and morphology of final product. Therefore, we attempt to control these reaction factors in order to improve the luminescent efficiency of phosphors. As a result of our study, when the acid catalyst (HCl) was used, emission intensity was higher than the case of base catalyst $(NH_4OH)$. The product prepared at $R_w=60$ indicated the maximum intensity. As the increase of the $R_w$ value, the particle was agglomerated and emission intensity was decreased. Finally, optimum drying temperature of gel was found to be$ 180^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2213-2216
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• 2009

A novel carbazole functionalized bis-$\beta$-diketone type organic ligand, 1,1′-(2,6-bispyridyl)bis-3-(9-ethylcarbazole- 3-yl)-1,3-propanedione ($H_2L$) and its corresponding lanthanide complexes $Eu_2(L)_3\;and\;Tb_2(L)_3$ were successfully prepared. The ligand and complexes were characterized in detail based on FT-IR spectra, $^1H$ NMR and elemental analysis. The observed UV-Vis absorption and photoluminescence properties of the complexes were investigated, it shows that the Eu(III) and Tb(III) ions can be sensitized efficiently by the ligand ($H_2L$) to some extent, in particular, the complex $Tb_2(L)_3$ exhibits a more excellent luminescence property than the Eu(III) complex. Meanwhile, the introduction of the carbazole moiety can enlarge the $\Pi$-conjugated system of the ligand and enhance the luminescent intensity of the complexes. The results show that the complexes would be used as excellent luminescent materials.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.207-212
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• 2003

The field emission and luminescent properties of carbon nanotubes (CNTs) that were straightened out by argon ion irradiation were investigated. Argon ion irradiation permanently straightened out both as-grown and screen-printed CNTs in the presence of a strong electric field. The straightening process enhanced the emission properties of CNT films by showing a decrease in turn-on field, an increase in total emission current, and a stable emission. Furthermore, the number of emission sites was confirmed to increase by observing the luminescent properties of CNT films after the straightening. The mechanism involved in the straightening of the CNTs is proposed and the enhancement in field emission is discussed in detail.