Application of liquid desiccant for enhanced lifetime of active matrix organic light emitting diodes
- PDF / 766,170 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 5 Downloads / 190 Views
Application of liquid desiccant for enhanced lifetime of active matrix organic light emitting diodes Byoung Duk Lee1, Yoon-Hyung Cho1, Minho Oh1, Yong Tak Kim1, Sang-Hwan Cho1, So Young Lee1, Yoon Ah Chung1, Seung Yong Song1, Jong Hyuk Lee1 and Sung Chul Kim2 1 2
OLED Precede Technology Team, Samsung Mobile Display, Gyunggi-Do 446-711, Korea OLED Development Department, Samsung Mobile Display, Gyunggi-Do 446-711, Korea
ABSTRACT To enhance the lifetime of large-sized active matrix organic light emitting diodes (AMOLEDs), we developed a liquid desiccant for encapsulation. The liquid desiccant was prepared by mixing nano-sized calcium oxide (CaO) powders and silicone binder including polyalkylalkenylsiloxane, polyalkylhydrogensiloxane and platinum compound. It was confirmed that liquid desiccant had an effect on absorption of penetrated moisture and oxygen through calcium tests. Also, the test cells encapsulated with only epoxy sealant dispensed at the edge of the cell developed dark spots within 100 hrs, which grew larger with time at 85 oC and 85 % R.H. On the other hand, the test cell sealed with epoxy sealant and liquid desiccant showed no dark spots and retained 97% of its initial luminance even after being stored for 800 hrs at 85 oC and 85 % R.H. Furthermore, the accelerating storage lifetimes of 31-inch bottom-emitting AMOLEDs with epoxy sealant and liquid desiccant showed about 1000 hrs. These results suggest that the liquid desiccant can be applied to encapsulation of large-sized AMOLEDs. INTRODUCTION AMOLEDs with various advantages such as wide viewing angle, thin thickness, short response time, low driving voltage, wide color gamut, high brightness and low power consumption has been developed and commercialized.[1-3] Some of the organic components and electrode metals in an OLED device will degrade when exposed to water.[4,5] To protect the OLED layers, many research groups have studied various methods and techniques for encapsulation of OLEDs, including thin film passivation.[6-8] Finally, for small-sized AMOLEDs equipped with smart phone (e.g. Samsung Galaxy S), edge sealing encapsulation with inorganic frit material heated locally by laser is enough to block permeation of water and fabricate reliable panels. However, for large-sized AMOLEDs, edge sealing with the frit has serious problems such as detachment from glasses by unbalanced mechanical stress under laser sealing. In order to improve mechanical strength and the life of an AMOLEDs display, new sealing technique, epoxy sealants and liquid desiccant were developed. Especially, liquid desiccant contained CaO known as an excellent desiccant. In this paper, we present the effect of liquid desiccant to improve lifetime of large-sized AMOLEDs. EXPERIMENT To prepare a liquid desiccant, nano-sized CaO powders were mixed with silicone binder including polyalkylalkenylsiloxane, polyalkylhydrogensiloxane and platinum compound in a
nitrogen-filled dry box with a water concentration of less than 1 p.p.m. 30-50 wt.% CaO powders with 100-200 nm of particle si
Data Loading...
