Nanometer-Thick SiN Films as Gas Barrier Coatings Densified by Vacuum UV Irradiation
Nanometer-Thick SiN Films as Gas Barrier Coatings Densified by Vacuum UV Irradiation
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DOI：
10.1021/acsanm.1c01862
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发表时间：
2021-09
影响因子：
5.9
通讯作者：
Tatsuki Sasaki;Lina Sun;Yu Kurosawa;Tatsuhiro Takahashi;Yoshiyuki Suzuri
中科院分区：
文献类型：
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作者：
Tatsuki Sasaki;Lina Sun;Yu Kurosawa;Tatsuhiro Takahashi;Yoshiyuki Suzuri
气体阻隔薄膜广泛用于电子和包装应用。它们也是需要高气体阻隔性能的柔性有机发光二极管（FOLED）的关键组件。在各种薄膜制造技术中，溶液处理薄膜封装（TFE）代表了一种低成本的 FOLED 制造方法。在 N2 气氛中溶液处理的全氢聚硅氮烷 (PHPS) 薄膜经真空紫外 (VUV) 诱导致密化后产生的纳米厚 SiN 薄膜可用作 TFE 阻挡薄膜。然而，纳米厚 PHPS 致密化过程尚未得到足够详细的研究。我们研究并讨论了 Si-N 键数、PHPS 薄膜成分和自由体积（存在于生成的 Si-N 网络中）对 VUV 诱导 PHPS 致密化过程的影响。研究发现，VUV 照射通过形成 Si-N 键引起氢的快速释放和薄膜致密化。使用X射线光电子能谱和动态二次离子质谱技术获得的结果以及计算的残余氢比率表明，薄膜组成与残余氢原子和Si-N键的数量密切相关。值得注意的是，纳米厚的PHPS薄膜致密化是一个相对缓慢的过程，其中Si-N网络中的自由体积由于VUV照射期间多个Si-N键同时断裂引起的原子重排而大大减少。我们相信，本文提出的结果可以作为开发具有相对高密度和优异气体阻隔性能（与真空处理阻隔膜所表现出的性能相当）的溶液处理纳米厚SiN薄膜的指南。
Gas barrier films are widely used in electronic and packaging applications. They are also critical components of flexible organic light-emitting diodes (FOLEDs) that require high gas barrier performance. Among the various film manufacturing techniques, solution-processed thin-film encapsulation (TFE) represents a low-cost FOLED fabrication method. The nanometer-thick SiN films produced following the vacuum ultraviolet (VUV)-induced densification of solution-processed perhydropolysilazane (PHPS) films in a N2atmosphere can potentially serve as TFE barrier films. However, the nanometer-thick PHPS densification process has not been examined in sufficient detail. We investigated and discussed the effects of the Si–N bond number, PHPS film composition, and free volume (present in the produced Si–N network) on the VUV-induced PHPS densification process. It was found that VUV irradiation caused rapid hydrogen release and film densification through the formation of Si–N bonds. The results obtained using the X-ray photoelectron spectroscopy and dynamic secondary ion mass spectrometry techniques, and the calculated residual hydrogen ratios, revealed that the film composition was strongly related to the number of residual hydrogen atoms and Si–N bonds. Notably, nanometer-thick PHPS film densification was a relatively slow process, in which the free volume in the Si–N network was considerably reduced by the atomic rearrangement induced by the simultaneous cleavage of several Si–N bonds during VUV irradiation. We believe that the results presented herein can potentially serve as a guideline for developing solution-processed nanometer-thick SiN films with relatively high density and excellent gas barrier performance (that is comparable to that exhibited by vacuum-processed barrier films).