Abstract
The molecular water concentration inside zinc phthalocyanine (ZnPc) thin films was measured. After exposure to air, gas effusion experiments show that the ZnPc layers contain (1.7±0.4)×10 20 water molecules per cm 3 , which corresponds to 1 H 2 O per 10 ZnPc units. We can distinguish a mobile and an immobilized population of H 2 O in ZnPc films. The mobile part effuses out at room temperature when exposing the films to a low pressure of 10 −2 mbar, whereas temperature activation is needed to reach a complete out-diffusion of water. The effusion process was observed to proceed with a diffusion coefficient D H 2 O of (1.3±0.3)×10 −10 cm 2 s −1 at 296 K. The rate of water effusion directly correlates with the timescale of the decrease of surface conductivity when exposing the layers to an equally low pressure. This indicates the existence of an electrically active surface layer of water molecules, which is refilled from the bulk of water molecules during the effusion process.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call