Evaluation of gas permeation barrier properties using electrical measurements of calcium degradation

Abstract

In this work, we developed a thin calcium degradation method introducing sensitive electrical resistance monitoring. We have demonstrated structural models of the inorganic/organic thin films to evaluate barrier properties against water and oxygen permeation. The time-dependent transmission curve of a multibarrier coated on both sides of the polyethersulfone substrate had a linear slope which was measured as 5.17 x 10(-3) gm(2) day at 20 degrees C and 60% relative humidity. This system can measure an accurate permeation rate with a high sensitivity in the measurable range of 10(1)-10(-6) gm(2) day. In addition, the test structure devised is applicable to various fabrication techniques for passivation layers with durability and ultralow permeability for flexible organic light emitting diodes.

Encapsulation for Improving the Efficiencies of Solar Cells

“…When calcium reacts with moisture, the thickness of calcium deposited decreases with time, when uniform surface oxidation of the calcium thin film is assumed. Hence the measured transmittance/resistance of calcium film varies with time as it gets oxidized and this change in optical/electrical property is correlated to the change in thickness, which further gives the value of WVTR [45,46].…”

“…Instead of placing the sealed calcium device in a humid environment, it is placed in oxygen environment with controllable humid conditions. The change in resistance gives the amount of calcium reacted with oxygen which finally gives OTR through the sealed test film [46].…”

Internal sensor compensation for increased Ca test sensitivity

“…Each data trace represents a different barrier aperture to Ca area aperture ratio (A B /A Ca ), covering seven orders of magnitude, with the ratios corresponding to a specific spacer size as indicated. The most common Ca test configuration in other work, [18][19][20][21] where the barrier area measured is the same as the Ca area (ratio = 1), is shown in solid blue. The aperture area representing a standard PV module is shown as a solid black line.…”

“…15,16 This test uses changes in the resistance of Ca traces in response to oxidation by permeated water as a means to measure very low WVTRs. [15][16][17][18][19][20][21] As barrier technologies improve, pushing the limits of the measurements, so must the characterization techniques. Thus, there is a consistent demand for higher sensitivity, decreased noise, and faster measurements.…”

Erratum: “Evaluation of gas permeation barrier properties using electrical measurements of calcium degradation” [Rev. Sci. Instrum. 78, 064701 (2007)]

“…͑Fig-ure 4 of Ref. 2 shows that same test films had parallel slopes and produced consistent permeation rates when using normalized current values.͒…”