Fe3O4/SiO2/YVO4:Eu3+ multifunctional nanoparticles are successfully synthesized by facile stepwise sol-gel processes. The multifunctional nanoparticles show a spherical shape with narrow size distribution (approximately 40 nm) and the phosphor shells are well crystallized. The Eu3+ shows strong photoluminescence (red emission at 619 nm, absorbance at 290 nm) due to an effective energy transfer from the vanadate group to Eu. Core-shell structured multifunctional nanoparticles have superparamagnetic properties at 300 K. Furthermore, the core-shell nanoparticles have a quick response time for the external magnetic field. These results suggest that the photoluminescence and magnetic properties could be easily tuned by either varying the number of coating processes or changing the phosphor elements. The nanoparticles may have potential applications for appropriate fields such as laser systems, optical amplifiers, security systems, and drug delivery materials.

Lu(Nb,Ta)O4:Eu3+ powders are synthesized by a solid-state reaction process using LiCl and Li2SO4 fluxes. The photoluminescence (PL) excitation spectra of the synthesized powders consist of broad bands at approximately 270 nm and sharp peaks in the near ultraviolet region, which are assigned to the Nb5+-O2− charge transfer of [NbO4]3− niobates and the f-f transition of Eu3+, respectively. The PL emission spectra exhibit red peaks assigned to the 5D0 → 7FJ transitions of Eu3+. The strongest peak is obtained at 614 nm (5D0 → 7F2), indicating that the Eu3+ ions are incorporated into the Lu3+ asymmetric sites. The addition of fluxes causes the increase in emission intensity, and Li2SO4 flux is more effective for enhancement in emission intensity than is LiCl flux. The substitution of Ta5+ for Nb5+ results in an increase or decrease in the emission intensity of LuNb1-xTaxO4:Eu3+ powders, depending on amount and kind of flux. The findings are explained using particle morphology, modification of the [NbO4]3− structure, formation of substructure of LuTaO4, and change in the crystal field surrounding the Eu3+ ions.

본 연구는 담녹조강 Tetraselmis suecica와 T. tetrathele의 인산염 흡수에 미치는 발광다이오드의 파장의 영향을 조사하였다. 파장은 청색 발광다이오드(LED; 450 nm), 황색 LED(590 nm), 적색 LED(630 nm) 그리고 형광램프(control)이며, 조도는 100 μmol m-2 s-1로 주사하였 다. T. suecica와 T. tetrathele의 최대흡수속도(ρmax)는 적색 LED에서 6.35 pmol cell-1 hr-1와 9.85 pmol cell-1 hr-1로 나타났으며, 반포화농도(Ks)는 9.43 μM와 21.2 μM로 나타났다. 이는 적색 LED 아래에서 T. suecica와 T. tetrathele가 다른 파장보다 영양염에 대한 친화성이 높다는 것으로 의미한다. 따라서 경제성 및 생산성 향상을 위한 Tetraselmis 배양시스템(광배양기)의 최적 광원은 낮은 영양염 상태에서도 높은 생장속도를 보이는 적색 LED가 적합할 것으로 판단된다.

The study aimed to determine effects of light emitting diode (LED) and the ultraviolet radiation (UVA) light of plant factory on plant growth and ascorbic acid content of spinach (Spinacia oleracea cv. Shusiro). Plants were grown in a NFT (Nutrient Film Technique) system for 28 days after transplanting with fluorescent light (FL, control), LEDs and UVA (Blue+UVA (BUV), Red and Blue (R:B(2:1)) + UVA (RBUV), Red+UVA (RUV), White LED (W), Red and Blue (R:B(2:1)), Blue (B), Red (R)) under the same light intensity (130 μmol·m-2·s-1) and photoperiod (16/8h = day/night). All the light sources containing the R (R, RB, RUV, and RBUV) showed leaf epinasty symptom at 21 days after transplanting (DAT). Under the RUV treatment, the lengths of leaf and leaf petiole were significantly reduced and the leaf width was increased, lowering the leaf shape index, compared to the R treatment. Under the BUV, however, the lengths of leaf and leaf petiole were increased significantly, and the leaf number was increased compared to B. Under the RBUV treatment, the leaf length was significantly shorter than other treatments, while no significant difference between the RBUV and RB for the fresh and dry weights and leaf area. Dry weights at 28 days after transplanting were significantly higher in the R, RUV and BUV treatments than those in the W and FL. The leaf area was significantly higher under the BUV treatment. The ascorbic acid content of the 28 day-old spinach under the B was significantly higher, followed by the BUV, and significantly lower in FL and R. All the integrated data suggest that the BUV light seems to be the most suitable for growth and quality of hydroponically grown spinach in a plant factory.

웨어러블 광섬유 직물의 주요 요건은 의류에 적용하기 위해 높은 유연성을 전제로 해야 한다는 점과 인체의 평평한 부위뿐만 아니라 굴곡이 있는 구간에서도 발광 효과, 즉 휘도를 유지해야 한다는 점이다. 따라서 본 연구에서는 위 조건을 충족하는 웨어러블 광섬유 직물의 세부 구조를 직조(weaving) 타입과 자수(computer embroidery) 타입의 2가지 로 제작하였고, 이를 토대로 다음의 두 가지 조건에서 실험을 실시하였다. 첫째, 굴곡이 없는 평평한 상태에서의 웨어러블 광섬유 직물을 1㎝간격으로 총 10개의 측정점을 좌표화하여 그 휘도를 측정하였다. 둘째, 인체 부위 중 입체적 굴곡이 발생하는 팔뚝 부위에 가로 방향으로 웨어러블 광섬유 직물을 배치하고 1㎝ 간격으로 총 10개의 측정점을 좌표화하여 그 휘도값을 측정하였다. 그 결과 직조(weaving) 타입의 경우, 평평한 상태에서의 휘도값은 최대 5.23cd/㎡, 최소 2.74cd/㎡, 평균 3.56cd/㎡, 표준편차 1.11cd/㎡로 나타났고, 팔뚝 부위에서의 휘도값은 최대 7.92cd/㎡, 최소 2.37cd/㎡, 평균 4.42cd/㎡, 표준편차 2.16cd/㎡로 나타났다. 또한 자수(computer embroidery) 타입의 경우, 평평한 상태에서의 휘도값은 최대 7.56cd/㎡, 최소 3.84cd/㎡, 평균 5.13cd/㎡, 표준편차 1.04cd/㎡로 나타났고, 팔뚝 부위에서의 휘도값은 최대 9.62cd/㎡, 최소 3.63cd/㎡, 평균 6.13cd/㎡ 표준편차 2.26cd/㎡ 나타났다. 즉, 자수(computer embroidery) 타입의 경우가 직조(weaving) 타입의 경우에 비해 더 높은 발광 효과를 보였는데 이는 자수(computer embroidery) 타입의 세부 구조가 배면 소재로 인해 빛의 손실을 줄일 수 있었기 때문으로 사료된다. 또한 두 타입 모두에서 팔뚝 부위의 휘도가 평평한 상태에 비해 각각 124%, 119%로 나타나, 인체의 굴곡에도 본 웨어러블 광섬유 직물의 발광 효과가 우수하게 나타남을 알 수 있었다. 이는 빛의 파동설을 정의한 호이겐스의 원리(Huygens’ principle), 빛 파면의 진행 방향과 이루는 각도(θ)의 크기에 커지면 이와 비례하여 빛의 세기도 커진다는 호이겐스-프레넬-키르히호프 원리 (Huygens-Fresnel-Kirchhoff principle)와 일치하는 결과이다.

Three new asymmetric light emitting organic compounds were synthesized with diphenylamine or triphenylamine side groups; 10-(3,5-diphenylphenyl)-N,N-diphenylanthracen-9-amine (MADa), 4-(10-(3,5-diphenylphenyl)anthracen-9-yl)-N,N-diphenylaniline (MATa), and 4-(10-(30,50-diphenylbiphenyl-4-yl) anthracen-9-yl)-N,N-diphenylaniline (TATa). MATa and TATa had a PLmax at 463 nm in the blue region, and MADa had a PLmax at 498 nm. The EL efficiency and color coordinate values (respectively) were 10.3 cd/A and (0.199, 0.152; bluish-green) for the MADa device, 4.67 cd/A and (0.151, 0.177) for the MATa device, and 6.07 cd/A and (0.149, 0.177) for the TATa device. The TATa device had a high external quantum efficiency (EQE) of 6.19%, and its luminance and power efficiencies and life-time were more than twice those of the MADN device.

New type of White-Light Emitting Diode (WOLED) that emits three primary colors of red, green and blue has been demonstrated. WOLED is properly laid out with emitting layers so that all three wavelengths of light can be emitted by using fit energy level, and the organic functional layer named white balanced layer (WBL) is introduced. As for the material used as WBL, the experiment used NPB that has electron blocking effect with its large LUMO value. The color purity of such WOLED can be easily adjusted through the adjustment of the number of electron carriers injected into light emitting layer. In this of study, color coordinate was (0.341, 0.424) and light emitting efficiency was 16.5 cd/A at current density 10 mA/cm2, so the WOLED demonstrated highly efficient characteristics of over commercial level.

7,8,10-triphenylfluoranthene [TP-F], 7,10-diphenyl-8-p-tolylfluoranthene [DPT-F] and 7,10-diphenyl-8-p-cyanophenlyfluoranthene [DPC-F] were synthesized by using the Knoevenagel condensation and Diels–Alder addition. Multilayered EL devices were fabricated using these materials as non-doped blue emitting layers. DPT-F device including a methyl group has better thermal properties, a better luminance efficiency, a lower operating voltage, and a higher power efficiency than the TP-F device. TP-F showed skyblue CIE value of (0.192, 0.269) and 3.27cd/A at 10mA/cm2. DPT-F also showed sky-blue CIE value of (0.185, 0.252) and 2.31cd/A at 10mA/cm2.

ZnO micro/nanocrystals are formed by a vapor transport method. Mixtures of ZnO and TiO powders are used as the source materials. The TiO powder acts as a reducing agent to reduce the ZnO to Zn and plays an important role in the formation of ZnO micro/nanocrystals. The vapor transport process is carried out in air at atmospheric pressure. When the weight ratios of TiO to ZnO in the source material are lower than 1:2, no ZnO micro/nanocrystals are formed. However, when the ratios of TiO to ZnO in the source material are greater than 1:1, the ZnO crystals with one-dimensional wire morphology are formed. In the room temperature cathodoluminescence spectra of all the products, a strong ultraviolet emission centered at 380 nm is observed. As the ratio of TiO to ZnO in the source material increases from 1:2 to 1:1, the intensity ratio of ultraviolet to visible emission increases, suggesting that the crystallinity of the ZnO crystals is improved. Only the ultraviolet emission is observed for the ZnO crystals prepared using the source material with a TiO/ZnO ratio of 2:1.

ZnO crystals with different morphologies are synthesized through thermal evaporation of the mixture of Zn and Cu powder in air at atmospheric pressure. ZnO crystals with wire shape are synthesized when the process is performed at 1,000 oC, while tetrapod-shaped ZnO crystals begin to form at 1,100 oC. The wire-shaped ZnO crystals form even at 1,000 oC, indicating that Cu acts as a reducing agent. As the temperature increases to 1,200 oC, a large quantity of tetrapod-shaped ZnO crystals form and their size also increases. In addition to the tetrapods, rod-shaped ZnO crystals are observed. The atomic ratio of Zn and O in the ZnO crystals is approximately 1:1 with an increasing process temperature from 1,000 oC to 1,200 oC. For the ZnO crystals synthesized at 1,000 oC, no luminescence spectrum is observed. A weak visible luminescence is detected for the ZnO crystals prepared at 1,100 oC. Ultraviolet and visible luminescence peaks with strong intensities are observed in the luminescence spectrum of the ZnO crystals formed at 1,200 oC.

Ca3MgSi2O8:Eu2+(x = 0.003, 0.005, 0.007, 0.01, 0.03 mol) white phosphors for Light Emitting Diodes(LED) are synthesized with different concentrations of Eu2+ ions using a solid state reaction method. The crystal structures, surface and optical properties of the phosphors are investigated using X-Ray Diffraction(XRD), Scanning Electron Microscope(SEM) and photoluminescence(PL). The X-Ray Diffraction results reveals that the crystal structure of the Ca3MgSi2O8:Eu2+ is a monoclinic system. The particle size of Ca3MgSi2O8:Eu2+ white phosphors is about 1~5 μm, as confirmed by SEM images. The maximum emission spectra of the phosphors are observed at 0.01 mol Eu2+ concentration. The decrease in PL intensity in the Ca3MgSi2O8:Eu2+ white phosphors with Eu2+ concentration is interpreted by concentration quenching. The International Commission on Illumination(CIE) coordinate of 0.01 mol Eu doped Ca3MgSi2O8 is X = 0.2136, Y = 0.3771.

시설 토마토 온실에서 다양한 발광 램프가 장착된 트랩을 가지고 온실가루이의 유인 효과에 미치는 영향에 대하여 조사하였다. 설치된 램프의 종류는 청색, 황색 그리고 흰색 발광 램프가 장착된 트랩을 이용하였다. 실험 결과 청색 발광 램프가 설치된 트랩에서 110마리로 가장 많은 온실가루이 성충이 유인되었고 황색램프 트랩과 흰색램프 트랩에서는 각각 71마리와 45마리가 포획 되었다. 이때 청색 발광램프 트랩의 파장대역은 330nm에서 430nm를 나타내었다. 그러나, 황색광과 흰색광 발광램프 트랩에서도 청색광 램프의 파장대역을 가지고는 있었으나 한편으로 온실가루이가 회피하는 파장대역 또한 동시에 포함하고 있었다. 이 결과 이들 두 개의 트랩에서 보다 청색광 발광트랩이 유인 포획률이 높아 시설 토마토 온실에서 온실가루이의 방제와 예찰에 효과적으로 사용될 수 있을 것으로 판단되었다.

본 실험은 LED 광원이 시금치 품종 별 생육, 잎 형태 변화 및 세포 길이에 대한 영향을 구명하고자 수행하였다. 최아된 시금치(Spinacia oleracea.) 품종 ‘월드스타’와 ‘수시로’를 버미큘라이트에 육묘한 후 NFT 시스템에 정식 한 뒤 LED 적색광(R), 청색광(B), 혼합광(적색:청색=2:1)(RB) 및 백색광(W)에서 130μmol·m-2·s-1 PPFD 광도로 25일간 재배하였다. 정식 후 일주일 간격으로 25일 동안 엽장, 엽폭, 엽병, 엽수, 광합성률을 측정하였고, 상편생장지수(leaf epinasty index, LEI)는 잎이 최대로 전개된 후에 측정하였다. 상편생장이 발생된 잎 가운데와 가장자리를 자른 조직의 세포길이, 폭 및 세포면적은 400배율 광학현미경을 이용하여 측정하였다. 정식 후 25일째에는 엽면적, 뿌리길이, 지상부 및 지하부의 생체중, 건물중을 조사하였다. 지상부 생체중과 건물중, 엽수, 엽면적 모두 월드스타 품종이 수시로 품종에 비해 유의적으로 높았다. 건물중은 월드스타 품종의 경우 혼합광(RB)와 적색광(R) 두 처리구에서 청색광(B)와 흰색광(W) 두 처리보다 약 35% 유의적으로 높았다. 수시로 품종의 경우 혼합광(RB) 처리구에서 지상부 건물중이 가장 높아 건물중이 가장 낮았던 흰색광(W) 처리구에 비해 40% 높은 건물중 결과를 보였다. 두 품종 모두 혼합광(RB)와 적색광(R) 두 처리구에서만 정식 21일 이후 잎 상편생장(leaf epinasty)이 나타났고 적색광(R) 처리구에서 혼합광(RB) 처리구 보다 유의적으로 높아 잎 상편 생장은 적색광(R)과 관련이 있는 것을 알 수 있었다. 잎 가운데와 가장자리 부위 세포크기를 현미경으로 관찰한 결과 두 품종 모두 상편생장이 나타난 적색광(R) 처리구의 잎 가장자리 세포밀도가 잎 가운데 보다 낮은 것으로 나타나 앞서 보고된 연구결과들에서 제시한 상편생장과 잎 가운데와 가장자리 부위의 세포크기 차이 연관성을 뒷받침하고 있다. 또한 청색광(B)이 적색광(B)에서 발생되는 상편생장을 완화시켜주는 역할을 하는 것으로 보여 앞으로 두 광원의 적절한 혼합비율 규명이 필요한 것으로 판단된다. 또한, 엽형 변화가 심했던 수시로 품종보다는 월드스타 품종이 LED 광원을 이용한 식물공장 재배에 더 적합한 것으로 판단된다.

LuNbO4:0.2Yb3+,xTm3+ powders were prepared using a solid-state reaction process. The effects of the amount of Tm on up-conversion(UC) and down-conversion(DC) luminescence properties are investigated. X-ray diffraction patterns confirm that Yb3+ and Tm3+ ions are successfully incorporated into Lu sites. Under 980 nm excitation, the UC spectra of the powders predominantly exhibit strong near-infrared emission bands that peak at 805 nm, whereas weak 480 nm emission bands are observed as well. The emission bands are assigned to the 1G4→ 3H6 (480 nm) and 3H4→ 3H6 (805 nm) transitions of the Tm3+ ions via an energy transfer from Yb3+ to Tm3+; two- and three-photon UC processes are responsible for the 805 and 480 nm emissions, respectively. The DC emission spectra exhibit blue emission (1D2→ 3F4) of Tm3+ at 458 nm. The amount of Tm affects the emission intensity with the strongest emissions at x = 0.007 and 0.02 for the UC and DC luminescence, respectively. The results demonstrate that LuNbO4:Yb3+,Tm3+ phosphors are suitable for bio-applications.

Two different emitting compounds, 1-[1,1;3,1]Terphenyl-5-yl-6-(10-[1,1;3,1]terphenyl-5-ylanthracen-9-yl)-pyrene (TP-AP-TP) and Poly-phenylene vinylene derivative (PDY 132) were used to white OLED device. By incorporating adjacent blue and yellow emitting layers in a multi-layered structure, highly efficient white emission has been attained. The device was fabricated with a hybrid configuration structure: ITO/PEDOT (40 nm)/PDY-132 (8∼50 nm)/NPB (10 nm)/TP-AP-TP (30 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). After fixing TP-AP-TP thickness of 30 nm by evaporation, PDY-132 thickness varied with 8, 15, 35, and 50 nm by spin coating in device. The luminance efficiency of the white devices at 10 mA/cm2 were 2.93 cd/A∼6.55 cd/A. One of white devices showed 6.55 cd/A and white color of (0.290, 0.331).

4-Methyl-7-(10-phenyl-anthracen-9-yl)-chromen-2-one (PhAC), 4-Methyl-7-(10-naphthalen-1-yl-anthracen-9-yl)-chromen-2-one (1-NAC), 4-Methyl-7-(10-naphthalen-2-yl-anthracen-9-yl)-chromen-2-one (2-NAC), and 7-Anthracen-9-yl-4-methyl-chromen-2-one (AC) were synthesized through Suzuki aryl-aryl coupling reaction. Four compounds were used as emitting layer (EMLs) in non-doped OLEDs with the following structures: ITO/2-TNATA (60 nm)/NPB (15 nm)/EMLs (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). Non-doped devices showed luminescence efficiency of 2.14, 2.07, 1.52, and 1.12 cd/A at a current density of 10 mA/cm2.

New three emitting compounds, AK-1, AK-2 and AK-3 including diazocine moiety were synthesized through Suzuki-coupling reaction. Physical properties such as optical, electroluminescent properties were investigated. UV-visible spectrum of AK-1, AK-2 and AK-3 in film state showed maximum 392, 393 and 401 nm. PL spectrum of AK-1, AK-2 and AK-3 showed maximum emission wavelength of 472, 473 and 435 nm. Three compounds were used as EML in OLED device: ITO/2-TNATA (60 nm)/NPB (15 nm)/EML (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). AK-3 OLED device showed C.I.E value of (0.18, 0.26) and luminance efficiency of 0.51 cd/A at 10 mA/cm2. New derivatives including diazocine moiety were introduced as OLED emitting material and the EL efficiency was increased by the proper combination of core and side group.

New carbazole derivatives including coumarin moiety, 7-(3-Carbazol-9-yl-phenyl)-chromen-2-one (C-PCa), 7-(9-Phenyl-9H-carbazol-3-yl)-chromen-2-one (PCa-C), 7-[9-(3-Carbazol-9-yl-phenyl)-9H-carbazol-3-yl]-chromen-2-one (PDCa-C) were synthesized by Suzuki reaction. In film state, maximum UV-Vis absorption of three synthesized compounds appeared in the range 331 to 345 nm. PL spectrum of C-PCa, PCa-C and PDCa-C showed miximum emission wavelength of 449, 467 and 467 nm, respectively. C-PCa showed white emission of current efficiency of 1.16 cd/A, power efficiency of 0.59 lm/W and C.I.E of (0.26, 0.33). PCa-C showed current efficiency of 1.13 cd/A, power efficiency of 0.62 lm/W and C.I.E of (0.19, 0.27). PDCa-C showed the highest current efficiency of 1.34 cd/A, power efficiency of 0.62 lm/W and C.I.E of (0.18, 0.23).

4-methyl-7-(10-(pyren-1-yl)anthracen-9-yl)-2H-chromen-2-one (PAC), 7,7’-(anthracene-9,10-diyl)bis(4- methyl-2H-chromen-2-one) (CAC), 7-Anthracen-9-yl-4-methyl-chromen-2-one(AC), and 7-(naphthalen-1-yl)-2Hchromen-2-one (NC) were synthesized through Suzuki aryl-aryl coupling reaction. Optical and electroluminescence (EL) properties were evaluated by UV-visible absorption, photoluminescence (PL) spectra, and EL devices. Synthesized compounds were used as an emitting layer (EML) in non-doped device with the following structures: ITO/2-TNATA (60 nm)/NPB (15 nm)/synthesized compounds (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). Non-doped devices showed luminance efficiency (L.E.) of 1.38, 1.03, 1.12, and 0.39 cd/A at a current density of 10 mA/cm2.

7-(4-([1,1-biphenyl]-4-yl(9,9-dimethyl-9H-fluoren-2-yl)amino)phenyl)-4-methyl-2H-chromen-2-one (BPFA-C) including coumarin moiety was synthesized through Suzuki aryl-aryl coupling reaction. Optical and electrical properties were examined by UV-visible absorption spectra, PL spectra, and AC-2. UV-visible spectrum of BPFA-C in a film state showed maximum absorption wavelength of 367 nm. PL spectrum of BPFA-C show maximum emission wavelength of 511 nm. BPFA-C showed highly efficient luminescence property. EL spectrum of BPFA-C exhibited a maximum value of 504 nm and BPFA-C device provided luminescence efficiency of 4.59 cd/A, power efficiency of 3.17 lm/W, and CIE (x,y) of (0.25, 0.53) at a current density of 10 mA/cm².