Fabrication of Metal Grid Combined Ito Layer as a Flexible Composite Transparent
Jyun-Hong Chen1*, Tien-Lin Wu2, Chien-Hong Cheng2, Yu-Lun Chueh1
1Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan
2Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
* Presenter:Jyun-Hong Chen
Indium Tin Oxide (ITO) has become the mainstream of transparent optoelectronic devices because of its high conductivity and high visible light transmittance. However, because of the brittle behavior and limited supply of indium and the lack of flexibility of the ITO layer, it is not good for the flexible transparent electrode. In this work, we demonstrates the composite transparent conductive film combining an ITO film with high-transmittance high conductivity metal grid. This composite transparent conductive film is filled with ITO in the middle of a metal grid (Cr /Au), which combine the advantages of metal conduction and ITO transmission, while the width of the metal grid hole and bar will affect the conductivity and the transmittance of the composite conductive film. Here, we optimize the thickness of 26 nm-thick metal layer containing Cr (2nm) / Au (24nm) with a metal gird width of 75 μm and a bar width of 4 μm, yielding the sheet resistance and light transmittance of 54 Ω/□ and 87 % on a glass substrate measured in the wavelength of 550 nm. Furthermore, we also demonstrate the Cr/Au metal grid ITO conductive film on a flexible PEN substrate with a good sheet resistance of 220 Ω/□ and can be withstand the bending tests more 1000 times without any degradation. Furthermore, we demonstrate OLEDs with an EQE of 24 % using the Cr/Au metal grid ITO conductive film on a flexible PEN substrate as the transparent electrode, which is comparable with the identical OLEDs with the EOE of 28 % using pure 200 nm-thick ITO layer. Interestingly, the work function can be tunable, depending on different top metal selection.

Keywords: ITO, Metal grid, OLED, Flexible