P-96: Heat Transferable Thin Film Encapsulation Inserted Ag Thin Film to Improve Reliability of Flexible Displays

Kwon, Jeong Hyun; Im, Hyeon‐Gyun; Bae, Byung Seong; Chang, Ki Soo; Park, Sang‐Hee Ko; Choi, Kyung Cheol

doi:10.1002/sdtp.10958

Cited by 4 publications

(6 citation statements)

References 15 publications

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“…Four types of thin-film encapsulations were undertaken to analyze the thermal conductivity effect according to the presence and thickness of the Ag thin film (Figure 6b). 25 The first TFE structure was fabricated using only Al 2 O 3 and an S-H nanocomposite with very low thermal conductivity (TFE without Ag). The second TFE structure incorporated the proposed DMD-TFE structure with a 15 nm thick Ag film (TFE with Ag 15 nm).…”

Section: Resultsmentioning

confidence: 99%

“…Here, we propose a DMD-based TFE (DMD-TFE) as a new attempt to solve technical problems preventing the realization of flexible OLEDs by combining three materials with different effects together. , We introduce a Ag film for use in the TFE and investigate the bending characteristics and heat dissipation effect of the DMD-TFE layer. Regarding the use of the TFE, aluminum oxide (Al 2 O 3 ) was used to create a dielectric film in the DMD structure due to its electrically insulating properties .…”

Section: Introductionmentioning

confidence: 99%

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Functional Design of Dielectric–Metal–Dielectric-Based Thin-Film Encapsulation with Heat Transfer and Flexibility for Flexible Displays

Kwon

Choi

Jeon

et al. 2017

ACS Appl. Mater. Interfaces

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In this study, a new and efficient dielectric-metal-dielectric-based thin-film encapsulation (DMD-TFE) with an inserted Ag thin film is proposed to guarantee the reliability of flexible displays by improving the barrier properties, mechanical flexibility, and heat dissipation, which are considered to be essential requirements for organic light-emitting diode (OLED) encapsulation. The DMD-TFE, which is composed of AlO, Ag, and a silica nanoparticle-embedded sol-gel hybrid nanocomposite, shows a water vapor transmission rate of 8.70 × 10 g/m/day and good mechanical reliability at a bending radius of 30 mm, corresponding to 0.41% strain for 1000 bending cycles. The electrical performance of a thin-film encapsulated phosphorescent organic light-emitting diode (PHOLED) was identical to that of a glass-lid encapsulated PHOLED. The operational lifetimes of the thin-film encapsulated and glass-lid encapsulated PHOLEDs are 832 and 754 h, respectively. After 80 days, the thin-film encapsulated PHOLED did not show performance degradation or dark spots on the cell image in a shelf-lifetime test. Finally, the difference in lifetime of the OLED devices in relation to the presence and thickness of a Ag film was analyzed by applying various TFE structures to fluorescent organic light-emitting diodes (FOLEDs) that could generate high amounts of heat. To demonstrate the difference in heat dissipation effect among the TFE structures, the saturated temperatures of the encapsulated FOLEDs were measured from the back side surface of the glass substrate, and were found to be 67.78, 65.12, 60.44, and 39.67 °C after all encapsulated FOLEDs were operated at an initial luminance of 10 000 cd/m for sufficient heat generation. Furthermore, the operational lifetime tests of the encapsulated FOLED devices showed results that were consistent with the measurements of real-time temperature profiles taken with an infrared camera. A multifunctional hybrid thin-film encapsulation based on a dielectric-metal-dielectric structure was thus effectively designed considering the transmittance, gas-permeation barrier properties, flexibility, and heat dissipation effect by exploiting the advantages of each separate layer.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Functional Design of Dielectric–Metal–Dielectric-Based Thin-Film Encapsulation with Heat Transfer and Flexibility for Flexible Displays

Kwon

Choi

Jeon

et al. 2017

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, the improvement in the heat‐transfer properties with Ag thickness was not linear. In the initial stage of the inserted Ag film, heat dissipation was obvious, which was due to the much higher thermal conductivity of metal (Ag) than those of Al 2 O 3 and the polymer layer . In the same total thickness of the Ag film, the temperature reduction using ENC‐E was larger than that of ENC‐B, ENC‐C, and ENC‐D (the temperature reduction of the three TFE structures was essentially equal), especially for the very thin Ag films.…”

Section: Resultsmentioning

confidence: 99%

“…However, devices with ENC‐E have three ultrathin Ag film layers, and heat can dissipate gradually. The advantage of the temperature reduction in devices with ENC‐E decreases when the Ag films are very thick because the ultrathin film has a lower thermal conductivity due to the size effect of the nanoscale thin film compared with that of a bulk material . However, a thick metal film has a low resistance to stress, and cracks can form .…”

Section: Resultsmentioning

confidence: 99%

“…To eliminate nitrogen gas from the device, a thermally conductive epoxy resin has been used in the literature to fill in the glass cover; however, the thermal properties are not excellent, though they are better than those of OLEDs based on conventional glass encapsulation . A thin‐film encapsulation (TFE) structure combined with a thick heat sink shows good heat‐transfer properties …”

Section: Introductionmentioning

confidence: 99%

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Heat Dissipation Properties of Thin‐Film Encapsulation by Insertion of a Metal Thin Film for Organic Light‐Emitting Diodes

Zhang

Dong

et al. 2018

Physica Status Solidi (a)

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Thin-film encapsulation (TFE) technology composed of alternating inorganic/ organic materials is a popular encapsulation technology for organic lightemitting diodes (OLEDs), showing excellent heat-transfer properties combined with a thick heat sink. TFE by inserting a metal thin film is proposed to improve the heat-transfer property of an OLED without a separate thick heat sink. According to the presence of metal and its thickness and position, the heat dissipation effect of TFE is compared and optimized via finite element simulations. An obvious temperature-reduction effect is observed by placing a metal thin film after each inorganic/organic unit compared with that found by placing a metal film after an inorganic/organic unit. Here, the TFE technology composed of alternating inorganic/organic/metal materials is defined as MET-TFE. At a power density of 900 KW m À2 , the highest internal temperatures of the devices were 70.14 C (with glass encapsulation), 72.37 C (with TFE) and 65.63 C (with MET-TFE). Furthermore, the simulated thermal analysis results show that the reduction rate of device temperature for a device with MET-TFE is comparatively faster than those of devices with TFE and glass encapsulation when increasing the convective heat-transfer coefficient. These results suggest that the MET-TFE structure can effectively improve heat dissipation properties.

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Approaches for Long Lifetime Organic Light Emitting Diodes

et al. 2020

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Organic light emitting diodes (OLEDs) have been well known for their potential usage in the lighting and display industry. The device efficiency and lifetime have improved considerably in the last three decades. However, for commercial applications, operational lifetime still lies as one of the looming challenges. In this review paper, an in-depth description of the various factors which affect OLED lifetime, and the related solutions is attempted to be consolidated. Notably, all the known intrinsic and extrinsic degradation phenomena and failure mechanisms, which include the presence of dark spot, high heat during device operation, substrate fracture, downgrading luminance, moisture attack, oxidation, corrosion, electron induced migrations, photochemical degradation, electrochemical degradation, electric breakdown, thermomechanical failures, thermal breakdown/degradation, and presence of impurities within the materials and evaporator chamber are reviewed. Light is also shed on the materials and device structures which are developed in order to obtain along with developed materials and device structures to obtain stable devices. It is believed that the theme of this report, summarizing the knowledge of mechanisms allied with OLED degradation, would be contributory in developing better-quality OLED materials and, accordingly, longer lifespan devices.

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P-96: Heat Transferable Thin Film Encapsulation Inserted Ag Thin Film to Improve Reliability of Flexible Displays

Cited by 4 publications

References 15 publications

Functional Design of Dielectric–Metal–Dielectric-Based Thin-Film Encapsulation with Heat Transfer and Flexibility for Flexible Displays

Functional Design of Dielectric–Metal–Dielectric-Based Thin-Film Encapsulation with Heat Transfer and Flexibility for Flexible Displays

Heat Dissipation Properties of Thin‐Film Encapsulation by Insertion of a Metal Thin Film for Organic Light‐Emitting Diodes

Approaches for Long Lifetime Organic Light Emitting Diodes

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