Using copper substrate to enhance the thermal conductivity of top-emission organic light-emitting diodes for improving the luminance efficiency and lifetime

Tsai, Yuh‐Shyan; Wang, Shun-Hsi; Chen, Chuan-Hung; Cheng, Ching‐Lan; Liao, Teh-Chao

doi:10.1063/1.3272110

Cited by 14 publications

(4 citation statements)

References 7 publications

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“…Besides, compared to the reported graphene based OLEDs which are usually bottom‐emitting from graphene covered glass or polyethylene terephthalate (PET) substrates, the TEOLEDs have much less optical absorption and wave guiding loss, enhanced light outcoupling, larger aperture ratio, and easier integration with the active‐matrix control circuits. Furthermore, the high heat dissipation coefficient of Cu may help to enhance the lifetime and stability of the as‐fabricated TEOLEDs 12…”

Section: Introductionmentioning

confidence: 99%

Micro/Nanoscale Spatial Resolution Temperature Probing for the Interfacial Thermal Characterization of Epitaxial Graphene on 4H‐SiC

Yue

Zhang

Wang

2011

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113

104

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Limited internal phonon coupling and transfer within graphene in the out-of-plane direction significantly affects graphene-substrate interfacial phonon coupling and scattering, and leads to unique interfacial thermal transport phenomena. Through the simultaneous characterization of graphene and SiC Raman peaks, it is possible, for the first time, to distinguish the temperature of a graphene layer and its adjacent 4H-SiC substrate. The thermal probing resolution reaches the nanometer scale with the graphene (≈1.12 nm) and is on the micrometer scale (≈12 μm) within SiC next to the interface. A very high thermal resistance at the interface of 5.30 (-0.46) (+0.46) x 10(-5) Km2 W(-1) is observed by using a Raman frequency method under surface Joule heating. This value is much higher than those from molecular dynamics predictions of 7.01(-1.05) (+1.05) x 10(-1) and 8.47(-0.75) (+0.75) x 10(-10) Km2 w(-1) for surface heat fluxes of 3 × 10(9) and 1 × 10(9) and 1 x 10(10) W m(-2) , respectively. This analysis shows that the measured anomalous thermal contact resistance stems from the thermal expansion mismatch between graphene and SiC under Joule heating. This mismatch leads to interface delamination/separation and significantly enhances local phonon scattering. An independent laser-heating experiment conducted under the same conditions yielded a higher interfacial thermal resistance of 1.01(-0.59) (+1.23) x 10(-4) Km2 W(-1). Furthermore, the peak width method of Raman thermometry is also employed to evaluate the interfacial thermal resistance. The results are 3.52 × 10(-5) and 8.57 × 10(-5) K m2 W(-1) for Joule-heating and laser-heating experiments, respectively, confirming the anomalous thermal resistance between graphene and SiC. The difference in the results from the frequency and peak-width methods is caused by the thermal stress generated in the heating processes.

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Section: Introductionmentioning

confidence: 99%

Micro/Nanoscale Spatial Resolution Temperature Probing for the Interfacial Thermal Characterization of Epitaxial Graphene on 4H‐SiC

Yue

Zhang

Wang

2011

Small

113

104

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“…For OLEDs, device performance, particularly lifetime, is closely related to their junction temperature [4]. The junction temperature of OLEDs can be measured using the K-factor method [33]. By measuring the junction temperature, we are able to predict the lifetime of an OLED panel accurately in a time saving manner.…”

Section: New Life Testing Methodsmentioning

confidence: 99%

Thermal behavior and indirect life test of large-area OLED lighting panels

et al. 2014

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In this work, we studied the thermal behavior and addressed the challenges of life testing of large area OLED devices. In particular, we developed an indirect method to accurately calculate the life time of large-area OLED lighting panels without physically life-testing the panels. Using small area OLEDs with structures identical with the tested panels, we performed the life tests at desired driving current densities at different temperatures and extracted the relationship between junction temperature and the lifetime for the particular device. By measuring the panel junction temperature during operation under the same current density and using the life time measured on small area test devices, we determine the lifetime of the panels based on the thermal dependence. We test this methodology by predicting the life time of white PHOLED panels and then physically testing the panels. The typical result for the lifetime to 80% of the initial luminance (LT80) of the panel at a constant dc current density of 10 mA/cm 2 (3800 cd/m 2 ), was predicted to be 526 hours in good agreement with the actual life-test at 10 mA/cm 2 of 512 hrs. This good agreement, confirmed in different experiments, validates this novel technique as a practical life time predictor of large-area OLED lighting panels in a time saving manner.

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“…The OLED device is composed of two electrodes and multiple organic layers. Therefore the above equation should be replaced with (2) [11]. Consider Comparing (3) for the current TEOLED structure, the key factors affecting the heat flow rate are the thermal conductivity ( ), substrate thickness ( ), and UV glue materials.…”

Section: Characteristics Comparison Of Different Teoled Devicementioning

confidence: 99%

Top-Emission Organic Light Emitting Diode Fabrication Using High Dissipation Graphite Substrate

Tsai

Huang

et al. 2014

International Journal of Photoenergy

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This study uses a synthetic graphite fiber as the heat dissipation substrate for top-emission organic light emitting diode (TEOLED) to reduce the impact from joule heat. UV glue (YCD91) was spin coated onto the substrate as the insulation layer. The TEOLED structure is (glass; copper; graphite) substrate/YCD91 glue/Al/Au/EHI608/TAPC/Alq3/LiF/Al/Ag. The proposed graphite fiber substrate presents better luminous performance compared with glass and copper substrate devices with luminance of 3055 cd/m2and current efficiency of 6.11 cd/A at 50 mA/cm2. When lighting period of different substrates TEOLED, the substrate case back temperature was observed using different lighting periods. A glass substrate element operating from 5 to 25 seconds at 3000 cd/m2luminance produced a temperature rate of 1.207°C/sec. Under 4000 cd/m2luminance the copper and graphite substrate temperature rates were 0.125°C/sec and 0.088°C/sec. Graphite component lifetime was determined to be 1.875 times higher than the glass components and 1.125 times higher than that of copper.

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Using copper substrate to enhance the thermal conductivity of top-emission organic light-emitting diodes for improving the luminance efficiency and lifetime

Cited by 14 publications

References 7 publications

Micro/Nanoscale Spatial Resolution Temperature Probing for the Interfacial Thermal Characterization of Epitaxial Graphene on 4H‐SiC

Micro/Nanoscale Spatial Resolution Temperature Probing for the Interfacial Thermal Characterization of Epitaxial Graphene on 4H‐SiC

Thermal behavior and indirect life test of large-area OLED lighting panels

Top-Emission Organic Light Emitting Diode Fabrication Using High Dissipation Graphite Substrate

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