The role of plasma technology in barrier coating deposition

Recently, the search of effective moisture and gas barrier coatings based on flexible plastics has been extensively explored for various applications such as food packaging, encapsulation of organic electronics, organic light-emitting diodes (OLED) and quantum dots, sealing of vacuum insulation panels, biomedical applications, renewable organic energy, and protective coatings, and so on. Several approaches have been developed to prepare the barrier layers. The employment of plasma technology in barrier layer deposition demonstrates a unique characteristic and superior advantages, which are significantly favorable in scale, quality, and cost. The high-quality barrier layer with low permeation rate is even achieved by roll-to-roll processing, including plasma technologies ranging from plasma enhanced physical vapor deposition (PEPVD), plasma-assisted/-enhanced chemical vapor deposition (PECVD/PACVD), to plasma-assisted/enhanced atomic layer deposition (PEALD/PAALD). In this paper, the preparations of barrier layers based on plasma technology are summarized as follows: the plasma source, plasma working environment, and mechanism of plasma-enhanced coating growth in PVD, PECVD, or PEALD. The purpose is to clarify the relationship of plasma technology with the preparation methods, barrier properties, and application fields, and indicate the fabrication of barrier, or even superior barrier, films in future.