• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.758-763
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• 2006

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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.426-433
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• 2008

We first demonstrated simultaneous patterning and passivation of P3HT active layer with photosensitive PVA. The passivation layers were obtained by annealing the organic layers after developing PVA and subsequent over-etching the P3HT layer. The fabricated OTFTs were electrically characterized. The OTFTs exhibited the mobility of ${\sim}5.9{\times}10^{-4}\;cm^2/V{\cdot}s$ and on/off current ratio of ${\sim}10^4$. After passivation, the results showed the extended lifetime of ${\sim}250$ hours with photosensitive PVA layer.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.195-198
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• 2008

In this paper, it was demonstrated that organic thin-film transistors (OTFTs) were fabricated with the organic passivation layer by vapor deposition polymerization (VDP) processing. In order to form polymeric film as a passivation layer, VDP process was also introduced instead of spin-coating process, where polymeric film was co-deposited by high-vacuum thermal evaporation from 6FDA and ODA followed by curing. In order to investigate by compared with different passivation layer, the other OTFTs is fabricated to passivation by Polyvinylalcohol using spincoating. We can see that two different ways of passivation layer affect electric characteristic of OTFTs. The initial electric characteristic of OTFTs before passivation such as field effect mobility, threshold voltage, and on-off current ratio are $0.24cm^2/Vs$, -3V, and $10^6$, respectively. Then after polyimide passivation layer, field effect mobility change from $0.24cm^2/Vs$ to $0.26cm^2/Vs$, threshold voltage from -3V to 1V and on-off current ratio from $10^6$ to $10^6$, respectively. In the case of polyvinylalcohol passivation, the initial electric characteristic of OTFTs before passivation such as field effect mobility, threshold voltage, and on-off current ratio are $0.13cm^2/Vs$, 0V, and $10^6$, respectively. Then after polyvinylalcohol passivation layer, field effect mobility changes from $0.13cm^2/Vs$ to $0.13cm^2/Vs$, threshold voltage from 0V to 2V, and on-off current ratio from $10^6$ to $10^5$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.269-270
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• 2005

A hybrid passivation method using parylene and silicon dioxide combination layer for a flexible organic light emitting diode (FOLED) was applied on a polycarbonate substrate. A parylene coating by vapor polymerization method is a highly effective passivation process for the FOLED, and it applies all top surface and the edges of the FOLED device. In order to minimize the permeation of moisture and oxygen from the top surface of the device, an additional layer of silicon dioxide was deposited over the parylene coated layer. It was found that the water vapor transmittance rate (WVTR) of parylene (15 m-in-thickness) / SiO2 (0.3$\mu$m-in-thickness) combination layers deposited on polycarbonate film was decreased under the value of 10-3 g/m2day. The FOLED with the hybrid passivation showed remarkably longer lifetime characteristics in the ambient conditions than the non-passivated FOLED. The lifetime of the passivated FOLED was 400 hours and it was more than ten times over the lifetime of the convectional non-passivated FOLED.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.198-198
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• 2009

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.1
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• pp.6-9
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• 2020

Thin film transistors (TFTs) with large-area, high mobility, and high reliability are important factors for next-generation displays. In particular, thin transistors based on IGZO oxide semiconductors are being actively researched for this application. In this study, several methods for improving the reliability of a-IGZO TFTs by applying various materials on a passivation layer are investigated. In the literature, inorganic SiO₂, TiO₂, Al₂O₃, ZTSO, and organic CYTOP have been used for passivation. In the case of Al₂O₃, excellent stability is exhibited compared to the non-passivation TFT under the conditions of negative bias illumination stress (NBIS) for 3 wavelengths (R, G, B). When CYTOP passivation, SiO₂ passivation, and non-passivation devices were compared under the same positive bias temperature stress (PBTS), the Vth shifts were 2.8 V, 3.3 V, and 4.5 V, respectively. The Vth shifts of TiO₂ passivation and non-passivation devices under the same NBTS were -2.2 V and -3.8 V, respectively. It is expected that the presented results will form the basis for further research to improve the reliability of a-IGZO TFT.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1779-1783
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• 2006

The hybrid thin-film (HTF) passivation layer composed of the UV curable acrylate layer and MS-31 (MgO:SiO2=3:1wt%) layer was adopted in organic light emitting diode (OLED) to protect organic light emitting materials from penetrations of oxygen and water vapors. The moisture resistance of the deposited HTF layer was measured by the water vapor transmission rate (WVTR). The results showed that the HTF layer possessed a very low WVTR value of lower than $0.007g/m^2$ per day at $37.8^{\circ}C$ and 100% RH. Therefore, the HTF on the OLED was found to be very effective in protect what from the penetrations of oxygen and moisture.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.267-268
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• 2005

In this paper, the inorganic-organic thin film encapsulation layer was newly adopted to protect the organic layer from moisture and oxygen. Using the electron beam, Sputter and Spin-Coater system, the various kinds of inorganic and organic thin-films were deposited onto the Ethylene Terephthalate(PET) and their interface properties between organic and inorganic layer were investigated. In this investigation, the SiON and Polyimide(PI) layer showed the most suitable properties. Under these conditions, the WVTR(water vapour transition rate) for PET can be reduced from level of 0.57 g/$m^2$/day (bare subtrate) to $1{\times}10^{-5}$ /$m^2$/day after application of a SiON and Polyimide layer. These results indicates that the SiON/PI/SiON/PI/PET barrier coatings have high potential for flexible organic light-emitting diode(OLED) applications.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.893-896
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• 2003

Plasma polymerized para-xylene (PPpX) thin films deposited by plasma enhanced chemical vapor deposition (PECVD) were used to passivate the organic light emitting diodes (OLEDs). For OLEDs, indium tin oxide (ITO), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD), tris(8-hydroxyquinoline) aluminum $(Alq_{3})$ and aluminum (Al) were used as the anode, the hole transport layer (HTL), the emitting layer (EML) and the cathode, respectively. The OLED device with the PPpX passivation film (passivated device) showed similar electrical and optical characteristics to those of the OLED device without the PPpX passivation film (control device), indicating that the PECVD process did not degrade the performance of the OLEDs notably. The lifetime of the passivated device was two times longer than that of the control device. Passivation of OLEDs with PPpX films also suppressed the growth of dark spots. The density and size of dark spots of the passivated device were much smaller than those of the control device.

• Journal of the Korean institute of surface engineering
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• v.45 no.1
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• pp.20-24
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• 2012

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 $O_2$ and $H_2O$ and improve life time characteristics. Red OLED doped with 1 vol.% Rubrene in $Alq_3$ was used as a basic device. The films consist of ITO(150 nm)/ELM200_HIL(50 nm)/ELM002_HTL(30 nm)/$Alq_3$: 1 vol.% Rubrene(30 nm)/$Alq_3$(30 nm) and LiF(0.7 nm)/Al(100 nm) which were formed in that order. Using LiF/$SiN_x$ 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 $cd/m^2$ of OLED/LiF/$SiN_x$/E1/$SiN_x$ was 710 hours which showed about 1.5 times longer than OLED/LiF/$SiN_x$/E1 with 498 hours. futhermore, OLED/LiF/$SiN_x$/E1/$SiN_x$/E1/$SiN_x$ with 1301 hours showed about twice than OLED/LiF/$SiN_x$/E1/$SiN_x$ which demonstrated that superior characteristics of life time was obtained in multilayer passivation film. Through the above result, it was suggested using LiF/$SiN_x$ 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 $SiN_x$ inorganic layers with relatively large thermal stress.