유리성형용 카본금형의 표면조도에 미치는 고출력 스퍼터링 조건의 영향

주성후,양재웅 한국응용과학기술학회 2024 한국응용과학기술학회지 Vol.41 No.1

In this study, the various process conditions for high-power DC Magnetron Sputtering (DCMS) on the surface roughness of carbon thin films were investigated. The optimal conditions for Si/C coating were 40min for deposition time, which does not deviate from normal plasma, to obtain the maximum deposition rate, and the conditions for the best surface roughness were –16volt bias voltage and 400watt DC power with 1.3x10-3torr chamber pressure. Under these optimal conditions, an excellent carbon thin film with a surface roughness of 1.62nm and a thickness of 724nm was obtained. As a result of XPS analysis, it was confirmed that the GLC structure (sp2 bonding) was more dominant than the DLC structure (sp3 bonding) in the thin film structure of the carbon composite layer formed by DC sputtering. Except in infrequent cases of relatively plasma instability, the lower bias voltage and applied power induces smaller surface roughness value due to the cooling effect and particle densification. For the optimal conditions for Graphite/C composite layer coating, a roughness of 36.3 nm and a thickness of 711 nm was obtained under the same conditions of the optimal process conditions for Si/C coating. This layer showed a immensely low roughness value compared to the roughness of bare graphite of 242 nm which verifies that carbon coating using DC sputtering is highly effective in modifying the surface of graphite molds for glass forming.

SiN_x 박막에 의한 OLED 소자의 보호막 특성

주성후,Ju Sung-Hoo 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.8

We has been studied the thin film encapsulation effect for organic light-emitting diodes (OLED). To evaluate the passivation properties of the passivation layer materials, we have carried out the fabrication of green light emitting diodes with ultra violet(UV) light absorbing polymer resin, $SiO_2,\;and\;SiN_x$, respectively. From the measurement results of shrinkage properties according to the exposure time to the atmosphere, we found that $SiN_x$ thin film is the best material for passivation layer. We have investigated the emission efficiency and life time of OLED device using the package structure of $OLED/SiN_x/polymer$ resin/Al/polymer resin. The emission efficiency of this OLED device was 13 lm/W and life time was about 2,000 hours, which reach 95 % of the performance for the OLED encapsulated with metal.

Al/Ta₂O/SiO₂/p-Si capacitor의 전기적 특성

양해석,주성후 中央大學校 基礎科學硏究所 1995 基礎科學硏究所 論文集 Vol.9 No.-

Thin films of ????? are deposited on p-type Si substrate by RF reactive sputtering method and are subsequently annealed in O₂ambient for 1 hour at 400℃. The measured index of refraction of ????? is found to decrease upon annealing indicating improved stoichiometry, which is in agreement with the results of AES analysis. The electrical characteristics of the as-deposited and annealed Al/?????/ SiO₂/p-Si are investigated. It is found from C-V measurements that, upon annealing, the flat-band voltage shifts to a more positive value resulting in a decrease in the effective charge to a negative value. Also the hysteresis in the C-V curve is almost removed by annealing. The I-V characteristics under reverse bias shows the Poole-Frenkel conduction mechanism in the lower applied field and current saturation due to depletion in the higher field range. The leakage current density is found to decrease upon annealing. The changes in these electrica1 characteristics upon annealing can be accounted for as being primarily due to the decrease in oxygen deficiency of ?????.

C545T가 첨가된 OLED 소자의 발광특성

주성후(Sung Hoo Ju),양재웅(Jae Woong Yang) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.2

To investigate the characteristics of green light-emitting OLED device, C545T material with Alq 3 was doped in the OLED device of ITO(1500)/2-TNATA(400 A)/NPB(80 A)/Alq₃:C545T(160 A)/Alq₃(240 A)/LiF(3 A)/ Al(2400 A) structure, which was used as a activator at the respective concentration of 0.5 vol.%, 1 vol.%, 2 vol.% and 3 vol.%. It was observed from the experiments that the device efficiency firstly increased with the increase of C545T concentration and the maximum efficiency of 10.9 cd/A and 4.28 ㏐/W was obtained at C545T concentration of 1 vol.%, and then the device efficiency decreased as the C545T activator concentration increased above 2 vol.% contents, while the longest lifetime of over 750 hours was obtained at C545T concentration of 1 vol.%.

OLED소자의 수명에 미치는 다층 보호막의 영향

주성후(Sung Hoo Ju),양재웅(Jae Woong Yang) 한국표면공학회 2012 한국표면공학회지 Vol.45 No.1

Multilayer passivation film on OLED with organic/inorganic hybrid structure as to diminish the thermal stress and expansion was researched to protect device from the direct damage of O2 and H2O and improve life time characteristics. Red OLED doped with 1 vol.% Rubrene in Alq3 was used as a basic device. The films consist of ITO(150 nm)/ELM200_HIL(50 nm)/ELM002_HTL(30 nm)/ Alq3: 1 vol.% Rubrene(30 nm)/Alq3(30 nm) and LiF(0.7 nm)/Al(100 nm) which were formed in that order. Using LiF/SiNx as a buffer layer was determined because it significantly improved life time characteristics without suffering damage in the process of forming passivation film. Multilayer passivation film on buffer layer didn"t produce much change in current efficiency, while the half life time at 1,000 cd/㎡ of OLED/LiF/SiNx/E1/SiNx was 710 hours which showed about 1.5 times longer than OLED/LiF/SiNx/E1 with 498 hours. futhermore, OLED/LiF/SiNx/E1/SiNx/E1/SiNx with 1301 hours showed about twice than OLED/LiF/SiNx/E1/SiNx which demonstrated that superior characteristics of life time was obtained in multilayer passivation film. Through the above result, it was suggested using LiF/SiNx as a buffer layer could reduce the damage from the difference of thermal expansion coefficient in OLED with protective films, and epoxy layer in multilayer passivation film could function like a buffer between SiNx inorganic layers with relatively large thermal stress.

전파 정류 교류 구동 방식에 의한 OLED의 전계발광 특성

서정현,주성후 한국재료학회 2022 한국재료학회지 Vol.32 No.7

Single OLED and tandem OLED was manufactured to analyze the electroluminescence characteristics of DC driving, AC driving, and full-wave rectification driving. The threshold voltage of OLED was the highest in DC driving, and the lowest in full-wave rectification driving due to an improvement of current injection characteristics. The luminance at a driving voltage lower than 10.5 V (8,534 cd/m2) of single OLED and 20 V (7,377 cd/m2) of a tandem OLED showed that the full-wave rectification drive is higher than that of DC drive. The luminous efficiency of OLED is higher in full-wave rectification driving than in DC driving at low voltage, but decrease at high voltage. The full-wave rectification power source may obtain higher current density, higher luminance, and higher current efficiency than the AC power source. In addition, it was confirmed that the characteristics of AC driving and full-wave rectification driving can be predicted from DC driving characteristics by comparing the measured values and calculated values of AC driving and full-wave rectification driving emission characteristics. From the above results, it can be seen that OLED lighting with improved electroluminescence characteristics compared to DC driving is possible using full-wave rectification driving and tandem OLED.

2원 첨가 적색 OLED 소자의 발광특성

김경민,주성후,Kim, Kyong-Min,Ju, Sung-Hoo 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.6

To invest the luminescent characteristics of red light emitting OLED device, a dual dopant system was incorporated into the emitting layer. The multiple layer OLED device structure was $ITO(1500\;{\AA})/HIL(200\;{\AA})/a-NPD(600\;{\AA})/EML(300\;{\AA})/Alq_3(200\;{\AA})/LiF(7\;{\AA})/Al(1800\;{\AA})$. The concentrations of the rubrene dopant were tested at 0 vol.%, 3 vol.%, 6 vol.% and 9 vol.%. The maximum device efficiency and life time were obtained at the rubrene dopant concentration of 6 vol.%. Emission spectrum and color coordinate of devices showed no relationship with rubrene dopant concentration. Experiment results show that rubrene dopant absorbs energy from $Alq_3$ host and transfer it to RD1 dopant acting as an energy intermediate and influencing the device efficiency, finally the red light is emitted from the RD1 dopant.

교류 구동 방법에 의한 유기전계발광소자 발광 특성의 모델

서정현,주성후,Seo, Jung Hyun,Ju, Sung Hoo 한국재료학회 2021 한국재료학회지 Vol.31 No.10

This paper proposes a mathematical model that can calculate the luminescence characteristics driven by alternating current (AC) power using the current-voltage-luminance (I-V-L) properties of organic light emitting devices (OLED) driven by direct current power. Fluorescent OLEDs are manufactured to verify the model, and I-V-L characteristics driven by DC and AC are measured. The current efficiency of DC driven OLED can be divided into three sections. Region 1 is a section where the recombination efficiency increases as the carrier reaches the emission layer in proportion to the increase of the DC voltage. Region 2 is a section in which the maximum luminous efficiency is stably maintained. Region 3 is a section where the luminous efficiency decreases due to excess carriers. Therefore, the fitting equation is derived by dividing the current density and luminance of the DC driven OLED into three regions, and the current density and luminance of the AC driven OLED are calculated from the fitting equation. As a result, the measured and calculated values of the AC driving I-V-L characteristics show deviations of 4.7% for current density, 2.9 % for luminance, and 1.9 % for luminous efficiency.

청색 형광과 적색 인광 물질을 사용한 백색 OLED의 발광 특성

박찬석,주성후,Park, Chan-Suk,Ju, Sung-Hoo 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.11

We studied white organic light-emitting diodes using blue fluorescent and red phosphorescent materials. White single OLEDs were fabricated using SH-1 : BD-2 (3 vol.%) and CBP : $Ir(mphmq)_2(acac)$ (2 vol.%) as emitting layer (EML). The white single OLED using SH-1 : BD-2 (3 vol.% 8 nm) / CBP : $Ir(mphmq)_2(acac)$ (2 vol.% 22 nm) as emitting layer showed maximum current efficiency of 8.8 cd/A, Commission Internationale de l'Eclairage (CIE) coordinates of (0.403, 0.351) at $1,000cd/m^2$, and variation of CIE coordinates with ($0.402{\pm}0.012$, $0.35{\pm}0.002$) from 500 to $3,000cd/m^2$. The white tandem OLED using SH-1 : BD-2 (3 vol.% 12 nm) / CBP : $Ir(mphmq)_2(acac)$ (2 vol.% 18 nm) showed maximum efficiency of 19.6 cd/A, CIE coordinates of (0.354, 0.365) at $1,000cd/m^2$, and variation of CIE coordinates with ($0.356{\pm}0.016$, $0.364{\pm}0.002$) from 500 to $3,000cd/m^2$. Maximum current efficiency of the white tandem OLED was more twice as high as the single OLED. Our findings suggest that tandem OLED was possible to produce improved efficiency and excellent color stability.

평판 유리로 봉인된 다층 무기 박막을 갖는 OLED 봉지 방법

박민경,주성후,양재웅,백경갑,Park, Min-Kyung,Ju, Sung-Hoo,Yang, Jae-Woong,Paek, Kyeong-Kap 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.11

To study encapsulation method for large-area organic light emitting diodes (OLEDs), red emitting OLEDs were fabricated, on which LiF and Al were deposited as inorganic protective films. And then the OLED was attached to flat glass by printing method using epoxy. In case of direct coating of epoxy onto OLED by printing method, luminance and current efficiency were remarkably decreased because of the damage to the OLED by epoxy. In case of depositing LiF and Al as inorganic protective films and then coating of epoxy onto OLED, luminance and current efficiency were not changed. OLED lifetime was more increased through inorganic protective films between OLED and flat glass than that without any encapsulation (8.8 h), i.e., 47 (LiF/Al/epoxy/glass), 62 (LiF/Al/LiF/epoxy/glass), and 84 h (LiF/Al/Al/epoxy/glass). The characteristics of OLED encapsulated with inorganic protective films (attached to flat glass) showed the possibility of application of protective films.