Reserch of graphene-based device applied in water vapor transmission ate measurement

• Main Authors: Yung-Hsiang Hsieh, 謝永祥
• Other Authors: Cheng-Chung Lee
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/w3kee2

碩士 === 國立中央大學 === 光電科學與工程學系 === 103 === Flexible organic light emitting diode display is a candidate for next generation display device but the water vapor and oxygen is easy to damage the organic element. Therefore, the organic element needs barrier film to protect it. Water vapor transmission rate (WVTR, unit: g/m2/day)is used to evaluate the quality for encapsulation of organic element, which is estimated 10-6 g/m2/day There are two main ways to measure the WVTR for encapsulation of organic element but they have some disadvantages like that long time measurement and non-reusable. Recently, graphene is found to be a good gas sensor. Graphene has fast response time and sensitive characteristics. The charge transfer between the molecules and the graphene surface when the molecules absorb on graphene is in seconds. In this study, we made a fast WVTR-measurement system by graphene-based device. The graphene-based device is prepared by transferred the graphene which is grown by chemical vapor deposition (CVD) on glass subtrate first and then deposited the metal electrode with mask. The source voltage of graphene-based device kept 1V. Calculating the change of device current due to charge transfer between the molecules and the graphene surface that can be converted to how many water molecules absorb on graphene. Using physically model to fit the measurement data, and the fitting is very similar to experiment results. In the future, the graphene-based device measurement can be a new, fast and accurate way to measure WVTR. In this studt, we use a graphene-based device with average resistance about 2 ~ 2.5 kohm to measure a sample with WVTR ~ 5 x 10-4 g/m2/day under test conition: temperatue 35 ± 3 ℃, relative humidity 85 % in about one hour. The current change rate at the device is 72 %.