• Transactions on Electrical and Electronic Materials
• /
• 제11권2호
• /
• pp.85-88
• /
• 2010

Deep blue organic light emitting diodes (OLEDs) were fabricated using 5 wt.% doped BCzVBi with various blue host materials such as NPB, DPVBi, MADN and TPBi. A blue OLED device, using DPVBi as host material, was constructed via NPB ($500\;{\AA}$) / DPVBi:BCzVBi ($200\;{\AA}$) / Bphen ($300\;{\AA}$) / LiF ($20\;{\AA}$) / Al ($1,000\;{\AA}$) and it shows a maximum luminescence of $4,838\;cd/m^2$, a current density of $32.7\;mA/cm^2$, a luminous efficiency of 3.3 cd/A and CIExy coordinates of (0.19, 0.15) at 4.5 V whereas the luminous efficiencies and CIExy coordinates of other blue OLEDs using NPB, MADN and TPBi as host materials have 1.1, 2.6 and 2.0 cd/A and (0.15, 0.11), (0.15, 0.10) and (0.15, 0.10), respectively. Energy transfer mechanisms between BCzVBi and its host materials were discussed with an energy band structure of host materials.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.490-491
• /
• 2007

We have investigated dielectric polarization in organic light-emitting diodes using 8-hydroxyquinoline aluminum$(Alq_3)$ as an electron transport and emissive material. We analyzed the dielectric polarization of organic light emitting diodes using impedance. Impedance characteristics was measured complex impedance Z and phase ${\theta}$ in the frequency range of 40Hz to $10^8Hz$. We obtained dielectric constant and loss tangent (tan ${\delta}$) of the device. From these analyses, we are able to interpret a dielectric dispersion and dielectric absorption contributed by an interfacial and orientational polarization.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
• /
• pp.272-276
• /
• 2004

Great strides in organic light emitting device (OLED) technology have resulted in a number of commercial products. To continue this growth into large area displays, for example televisions, an understanding of the mechanisms that drive the OLED device efficiency and lifetime performance is critical. In this work, we consider maximizing the efficiency lifetime product based on phosphorescent OLED ($PHOLED^{TM}$) technology. We report green PHOLEDs with luminous efficiency of 82 cd/A, 5.7 V and 10,000 hours lifetime at 1,000 cd/$m^2$,red PHOLEDs with CIE of (0.67,0.33), 11 cd/A and 35,000 hours lifetime at 500 cd/$m^2$ and recent progress in blue demonstrating efficiencies of 18 cd/A at 200 cd/$m^2$.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.391.1-391.1
• /
• 2014

광물질로 인광물질을 사용한 유기발광다이오드(Organic Light Emitting Diode, OLED)는 재결합에 의해 형성된 여기자를 발광에 모두 이용할 수 있기 때문에 내부 양자효율이 100%로 알려져 있다. 하지만 유기층에서 발생된 빛이 소비자에게 전달되기까지의 경로에서 발생되는 wave guiding effect로 인해, 발생된 빛의 20%만이 전달된다. 특히 bottom emission type의 OLED에서 glass와 air사이의 굴절률이 달라 발생되는 전반사에 의해 손실되는 빛의 양은 35%에 달한다. 따라서 본 연구에서는 glass와 air사이의 전반사를 줄이고 광추출을 위해 습식 방법으로 hemisphere type의 ZnS를 제작하였다. 제작된 ZnS는 직경 200nm까지 성장하였으며, 이렇게 제작된 ZnS nano lens가 적용된 OLED device에서 휘도가 20% 이상 향상되는 것을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
• /
• pp.1703-1705
• /
• 2007

Before the ultra-violet glue encapsulation, the research evaporated LiF thin film on device surface to be the extra packaging layer for improving the lifetime of organic light-emitting diode. The formula of UV glue was specially developed. We found 100 nm LiF is the optimum thickness. The best lifetime obtained by using LiF and special UV glue is 2.4 times longer than those by commercial UV glue.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
• /
• pp.435-438
• /
• 2008

We demonstrated the efficient blue organic light-emitting diodes (OLEDs) by employing diarylamino-fluorene derived blue fluorescent molecules as dopants. Among those, a device exhibited blue emission with the luminous efficiency of 11.2 cd/A at $20\;mA/cm^2$, the external quantum efficiency of 9.7% at $20\;mA/cm^2$, and the $CIE_{x,y}$ coordinates of (x=0.163, y=0.259) at 8V.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
• /
• pp.1408-1409
• /
• 2005

Organic light-emitting diodes (OLEDs) of metalsemiconductor-metal (MSM) structure have been fabricated by using m-MTDATA [4,4',4"-tris (3-methylphenylphenylamino) triphenylamine] as a hole-injection layer (HIL). The m-MTDATA is shown to be an effective hole-injecting material for the OLED, in that the insertion of m-MTDATA greatly reduces the roughness of anode surface and improves the device performance.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.490-491
• /
• 2007

We have investigated dielectric dispersion and absorption in organic light-emitting diodes using 8-hydroxyquinoline aluminum($Alq_3$) as an electron transport and emissive material. We analyzed the dielectric dispersion and absorption of organic light emitting diodes using impedance characteristics measurement by the auto-balancing bridge technique of ITO/$Alq_3$/Al. Impedance characteristics was measured complex impedance Z and phase e in the frequency range of 40Hz to $10^8Hz$. We obtained dielectric constant and loss tangent (tan $\delta$) of the device. From these analyses, we are able to interpret a dielectric dispersion and dielectric absorption contributed by an interfacial and orientational polarization.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.533-534
• /
• 2005

Temperature-dependent current-voltage characteristics of organic light-emitting diodes(OLEDs) were studied in a device structure of ITO/TPD/$Alq_3$/Al. The OLEDs were based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-l,1'-diphenyl-4,4'-diamine(TPD) as a hole transport and tris(8-hydroxyquinoline) aluminum($Alq_3$) as an electron transport and emissive material. The current-voltage characteristics were measured in the temperature range of 10K and 300K. We analyzed an electrical conduction mechanism of the OLEDs using space-charge-limited current(SCLC) and Fowler-Nordheim tunneling.

• 한국전기전자재료학회논문지
• /
• 제23권2호
• /
• pp.124-127
• /
• 2010

We have fabricated organic white light emitting device by two colors from yellow fluorescence material (5,6,11,12)-Tetraphenylnaphthacene(Rubrene) and blue phosphorescent material (iridum-bis(4,6-difluorophenylpyridinato-N,C2)-picolinate(FIrpic). The threshold voltage is 5.3 V, and the brightness reaches 1000 cd/$m^2$ at 11 V, 14.5 mA/$m^2$. The color of the light corresponds to a CIE coordinate of (0.30, 0.38). The highest efficiency of the device can reach 9.5 cd/A or 5.5 lm/W at 6 V, 0.1 mA/$m^2$.