於聚對苯二甲酸乙二酯軟性基板上以低溫電漿輔助化學氣相沉積多層碳氮化矽/聚苯乙烯高性能水氣阻障膜

Abstract

有機元件像是，有機發光二極體、太陽能電池，在元件內部的電極、反應的主體都極易遭受到水氣和氧氣的攻擊，導致元件損壞。為了要延長有機元件的壽命，有機元件的封裝面臨了許多不可避免挑戰。最近有一個較為普遍的方法叫做“薄膜封裝“，他是直接在元件的基板上，鍍一層阻氣的薄膜。但是這之中還是有許多的問題存在，例如：在鍍膜的過程中，由於溫度太高，導致熱應力殘留，而使阻水阻氣的效果大為降低。 因此，一個有效的水氣阻障層，碳氮化矽和複合的碳氮化矽、聚苯乙烯薄膜被成功的開發出來與製備。吾人利用VSZ (1,3,5-trimethyl-1,3,5-trivinylcyclo- trisilazane)與Styrene在低溫電漿輔助化學沉積的系統在軟性聚對苯二甲酸乙二酯基板上沉積SiCxNy和PS (Polystyrene)阻障層。且利用自行組裝的鈣氧化電阻變化式的高靈敏度水氣穿透量測儀去量測阻障層的效果。我們可以得到單層SiCxNy 100nm可以將WVTR (water vapor transmit rate)從3降到5×10-2 g/m2/day.多層結構SiCxNy 可以更有效的降低WVTR到6×10-3g/m2/day.而單層複合阻障層SiCxNy/PS可以有效的降低WVTR到8×10-3g/m2/day.最後我們利用四層複合阻障層SiCxNy/PS可以得到一個極低的WVTR，8×10-3g/m5/day. 再者，為了要證實多層阻障層的效果，我們利用一個快速檢測阻障層缺陷的方法去佐證。我們利用電鍍鎳的方式去找出阻障層缺陷的數量，然後發現缺陷的數量與WVTR有正相關，於是得到多層結構可以有效的降低WVTR。其主要原因為多層結構會導致缺陷的不連續，而延長了水氣穿透的路徑，和在沉積上方的阻障層時，下方薄膜的缺陷會被癒合，進而減少了水氣穿透的路徑。

Moisture and oxygen permeation barrier technology become critical in achieving the required lifetime reliability of flexible devices such as flexible organic light-emitting diode (FOLED) and flexible solar cells. To date, thin-film encapsulation using multilayered organic/inorganic barriers on flexible polymer substrate is the most promising. However, there are still several challenging issues such as defects and cost. This study first established a water-vapor-transmission-rate (WVTR) measurement system with a high sensitivity (~10-5 g/m2/day). Next we developed a high-performance moisture barrier (8x10-5 g/m2/day) on flexible PET substrate. This is achieved by an alternating organic barrier (plasma polymerized polystyrene, PPS)/inorganic barrier, silicon carbonitride (SiCxNy) multi-layered structure, using plasma-enhanced chemical vapor deposition (PECVD) at room temperature and without breaking the vacuum, based on 1,3,5-trimethyl-1,3,5-trivinylcyclo-trisilazane (VSZ) and styrene precursor, respectively. The effects of barrier materials, their thicknesses, and the numbers of layer on WVTR, and the controlling mechanism were also investigated. A single SiCxNy barrier layer (100 nm) effectively reduces the WVTR of a PET film from 3 g/m2/day to 5×10-2 g/m2/day. Multi-layered moisture barrier structures based on triple SiCxNy barrier layers or SiCxNy/PPS/SiCxNy (100 nm each) can further reduce WVTR to 6×10-3 and 8×10-3 g/m2/day, respectively. In summary, multi-layered barrier can effectively reduce WVTR as compared to single layer at the same total thickness. Also, moisture barrier materials consisting of alternating SiCxNy and PPS multi-layered stack (4-pair with a total thickness of 0.8 □m) can effectively reduce WVTR down to 8×10-5 g/m2/day. Through the pinhole decoration by Ni electro-deposition, the mechanism of high-performance WVTR in a multilayered barrier can be attributed to the much increase in diffusion paths due to a reduction of pinhole defects healed by the alternating deposited, upper layer.