Engineer,Industrial Technology Research Institute (ITRI)
Highly uniform white organic light-emitting diodes using printed metal mesh technology
Hao-Che Kao (*) , Hsin-Chu Chen
R2R Process Development Department, Electronics and Optoelectronic System Research Laboratories,Industrial Technology Research Institute, TAIWAN
We successfully developed a high open ratio (>92%) of metal mesh with TCO hybrid structure technology using the printing process of gravure printer and screen printer. A low sheet resistivity (6Ω/□) functional substrate (10cm x 10cm) with white organic light-emitting diode(WOLED) device was made. WOLED device with metal mesh achieved 114 (cd/A), 42.5 lm/W, and uniformity > 90 %. Especially, the uniformity has almost 13.5% enhancement than the without metal mesh of the same structure WOLED device.
The metal mesh hybrid structure printing technique has been developed to make metal mesh transparent conductors in Fig. 1. The metal mesh is fabricated on the TCO substructure by gravure printer process and printing insulator layer on the mesh line by screen printer process,the insulator layer was in order to avoid the OLED being affected by the surface roughness and short circuit  . As the result that compared to ITO or all other ITO alternatives, the metal mesh transparent conductor has the lowest sheet resistance of 6 (Ω/□), and good transmittance > 90%; Metal mesh hybrid structure type of transparent conductive film does not have this issue because the conductivity is achieved by metal lines whereas the transparency is insured by mesh holes. Higher transparency can be achieved by large mesh holes and more fine line.
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R2R OLED lighting process integration
a. Identifying, troubleshooting.
b. Solving the technical issues
c. Solving the production issues.
d. Device failure analysis.
1. Development of High efficiency and long lifetime OLED devices.
a. OLED structure evaluation and optical matching.
(Transmittance conductive layer analysis, materials test, refractive index matching, etc.)
b. Improvement of cluster evaporation process from single stack to multi-stack
c. Flexible OLED devices manufacture.
d. RD-line equipment maintain and turning.
2. Uniformity progress for large size and R2R OLED devices
a. Developed printing technology for the large-area fabrication.
b. Designed and fabricated the functional substrate in OLEDs and demonstrated the enhancement of OLEDs performance.
c. Work together with other departments to develop new material and new process.
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