• 전자공학회논문지 IE
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• 제43권2호
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• pp.1-6
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• 2006

Two-wavelength에 의한 백색 유기발광소자를 청색계열의 발광재료 DPVBi와 오렌지계열의 발광재료 Rubrene 물질을 사용하여 제작하였다. 소자의 구조는 glass/ITO/TPD$(225{\AA})$/DPVBi/Rubrene/BCP$(210{\AA})/Alq_3(225{\AA})/Al(1000{\AA})$로 하였다. 청색 발광층인 DPVBi와 오렌지색 발광층인 Rubrene층의 두께비율를 변화시켜 가면서 백색광을 구현하였다. 청색발광재료 DPVBi층의 두께가 210${\AA}$ 이고 오렌지색 발광재료의 Rubrene 층의 두께가 180${\AA}$일 때 구동전압 15V에서 $1000cd/m^2$ 휘도와 (0.29, 0.33)의 CIE 색좌표값을 갖는 백색광을 얻었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1050-1053
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• 2006

We fabricated white organic light emitting diodes consisting of three emitting layers of red-emitting DCM2 doped ${\alpha}-NPD$, blue-emitting DPVBi and green-emitting C545T doped Alq3. By optimizing the thickness of the hole-transport layer of ${\alpha}-NPD$ and the electron-transport layer of Alq3, efficient white OLEDs were obtained with a luminous efficiency of 4.40lm/W at luminance of $1000cd/m^2$, and a max-imum luminance of $51,939cd/m^2$

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2001년도 International Meeting on Information Display
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• pp.157-158
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• 2001

We synthesized Bis(3-N-ethylcarbazolyl) terephthalidene(BECP) and Bis(3-N-ethylcarbazolyl) cyanoterephthalidene (BECCP) and characterized EL properties of these materials. Our device shows a strong blue emission at 472 nm with a luminance efficiency of 0.9 lm/Wat a voltage, a current density. and a brightness of 8 V, 5.7 $mA/cm^2$, and 130 $cd/m^2$, respectively.

• 한국전기전자재료학회논문지
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• 제18권10호
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• pp.941-944
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• 2005

In this experiment, OLEDs(Organic Light Emitting Diodes) was fabricated to confirm effect of Plasma treatment which increase the hole injection characteristic from anode. Device structure was $ITO/2-TNATA/{\alpha}-NPD/DPVBi/BAlq/Alq_3/Al:Li$. We used DPVBi (4, 4 - Bis (2,2-diphenylethen-1-yls) - Biphenyl) as a blue emitting material. To optimize the process condition of plasma treatment, we used 2 gases of the oxygen and nitrogen gas under 120 mTorr with 100 W, 200 W, and 400 W plasma power. The current efficiency of $N_2$ plasma is more efficient than that of $O_2$ plasma. At $1000 cd/m^2$, we obtained the maximum current efficiency of 6.45 cd/A using $N_2$ gas with 200 W plasma power.

• 한국전기전자재료학회논문지
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• 제25권6호
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• pp.456-461
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• 2012

We studied the emission characteristics of white phosphorescent organic light-emitting diodes (PHOLEDs), which were fabricated using a two-wavelength method. To optimize emission characteristics of white PHOLEDs, white PHOLEDs with red/blue, blue/red and red/blue/red emitting layer (EML) structures were fabricated using a host-dopant system. In case of white PHOLEDs with red/blue structure, the best efficiency was obtained at a structure of red (15 nm)/blue (15 nm). But the emission color was blue-shifted white. In case of white PHOLEDs with blue/red structure, the better color purity and efficiency were observed at a blue (29 nm)/red (1 nm) structure. For additional improvement of color purity in white PHOLEDs with blue (29 nm)/red (1 nm) EMLs, we fabricated white PHOLEDs with red (1 nm)/blue (28 nm)/red (1 nm) structure. The current efficiency, external quantum efficiency, and CIE (x, y) coordinate were 27.2 cd/A, 15.1%, and (0.382, 0.369) at 1,000 $cd/m^2$, respectively.

• ETRI Journal
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• 제43권6호
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• pp.1093-1102
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• 2021

Microdisplays based on organic light-emitting diodes (OLEDs) have a small form factor, and this can be a great advantage when applied to augmented reality and virtual reality devices. In addition, a high-resolution microdisplay of 3000 ppi or more can be achieved when applying a white OLED structure and a color filter. However, low luminance is the weakness of an OLED-based microdisplay as compared with other microdisplay technologies. By applying a tandem structure consisting of two separate emission layers, the efficiency of the OLED device is increased, and higher luminance can be achieved. The efficiency and white spectrum of the OLED device are affected by the position of the emitting layer in the tandem structure and calculated via optical simulation. Each white OLED device with optimized efficiency is fabricated according to the position of the emitting layer, and red, green, and blue spectrum and efficiency are confirmed after passing through color filters. The optimized white OLED device with color filters reaches 97.8% of the National Television Standards Committee standard.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.109-109
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• 2018

Bacillus subtilis B22, a chemotrophic and aerobic bacterial strain was isolated from homemade kimchi, identified by 16S rRNA gene sequencing. B22 was primarily screened by biochemical, carbon source utilization tests. B22 was used to produce pectinase and ${\beta}$-glucosidase by submerged fermentation under different light sources. B22 was incubated in pectin media and basal media (pH 7.0) under blue, green, red and white light-emitting diodes (LEDs), fluorescent white light, and in darkness at $37^{\circ}C$, orbital shaker 150 rpm for 24 hours. Fermentation under blue LEDs maximized pectinase production ($71.59{\pm}1.6U/mL$ at 24 h) and ${\beta}$-glucosidase production ($56.31{\pm}1.6U/mL$ at 24 h). Further, the production of enzyme increased to pectinase ($156{\pm}1.28U/mL$) and ${\beta}$-glucosidase ($172{\pm}1.28U/mL$) with 3% glucose as a carbon source. Activity and stability of the partially purified enzymes were higher at pH 6.0 to 8.0 and $25-55^{\circ}C$. The effect on the metal ions $Na^+$ and $K^+$ and (moderateactivity) $Mn^{2+}$ and $Ni^{2+}$ increased activity, while $Hg^{2+}$, $Cu^{2+}$, $Fe^{2+}$, and $Fe^{2+}$ inhibited activity. EDTA, phenylmethylsulfonyl fluoride and 5,5-dithiobis (2-nitrobenzoicacid) reduced activity, while tetrafluoroethylene and 1,10-phenanthroline inhibited activity. The amylase was highly tolerant of the surfactants TritonX-100, Tween-20, Tween-80 and compatible with organic solvents methanol, ethanol, isoamylalcohol, isopropanol, t-butylalcohol and the oxidizing agents hydrogen peroxide, sodium perborate and sodium hypochlorite, although potassium iodide and ammonium persulfate reduced activity. These properties suggest utility of pectinase and ${\beta}$-glucosidase produced by B. subtilis B22 under blue LED-mediated fermentation for industrial applications.

• 한국전기전자재료학회논문지
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• 제27권1호
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• pp.45-49
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• 2014

We have fabricated white organic light-emitting diodes (OLEDs) using several thicknesses of electron-transport layer. The multi-emission layer structure doped with red and blue phosphorescent guest emitters was used for achieving white emission. 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was used as an electron-transport layer. The thickness of BCP layer was varied to be 20, 55, and 120 nm. The current efficiency, emission and recombination characteristics of multi-layer white OLEDs were investigated. The BCP layer thickness variation results in the shift of emission spectrum due to the recombination zone shift. As the BCP layer thickness increases, the recombination zone shifts toward the electron-transport layer/emission-layer interface. The white OLED with a 55 nm thick BCP layer exhibited a maximum current efficiency of 40.9 cd/A.

• 한국재료학회지
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• 제16권4호
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• pp.231-234
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• 2006

To obtain balanced white-emission and high efficiency of the organic light-emitting diodes (OLEDs), a deep blue emitter made of N,N'-diphenyl-N,N'-bis(1-naphthyl)- (1,1'-biphenyl)-4,4'-diamine (NPB) emitter and a new red emitter made of the Bis(2,4 -dimethyl-8-quinolinolato)(triphenylsilanolato)aluminum(III) (24MeSAlq) doped with red fluorescent 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H -pyran (DCJTB) were used and the device was tuned by varying the thickness of the DCJTB-doped 24MeSAlq and $Alq_3$. For the white OLED with 10 nm thickness DCJTB (0.5%) doped 24MeSAlq and 45 nm thick $Alq_3$, the maximum luminance of about 29,700 $Cd/m^2$ could be obtained at 14.8 V. Also, Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.28) at about 100 $Cd/m^2$, which is very close to white light equi-energy point (0.33, 0.33), could be obtained.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.345-346
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• 2008

We have studied an emission spectra of top-emssion organic light-emitting diodes(TEOLED) due to a change of cathode and organic layer thickness. Device structure is Al(100nm)/TPD(xnm)/$Alq_3$(ynm)/LiF(0.5nm)/cathode. And two different types of cathode were used; one is LiF(0.5nm)/Al(25nm) and the other is LiF(0.5nm)/Al(2nm)/Ag(30nm). While a thickness of hole-transport layer of TPD was varied from 35 to 65nm, an emissive layer thickness of $Alq_3$ was varied from 50 to 100nm for two devices. A ratio of those two layer was kept to be about 2:3. Al and Al/Ag double layer cathode devices show that the emission spectra were changed from 490nm to 560nm and from 490nm to 560nm, respectively, when the total organic layer increase. Full width at half maximum was changed from 67nm to 49nm and from 90nm to 35nm as the organic layer thickness increases. All devices show that view angle dependent emission spectra show a blue shift. Blue shift is strong when the organic layer thickness is more than 140nm. Devece with Al/Ag double layer cathode is more vivid.