Polyvinyl alcohol-based polarizers for new displays: molecules, processing and properties.

Li, Yao; Xie, Jiayu; Cheng, Hong; Wei, Xiaoying; Chen, Jie; You, Liangpeng; Chen, Wei · Soft Matter · 2025

basic_science · Level V

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Abstract

Polarizers are a key component of new display panels (<i>i.e.</i> liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs)), consisting of a polarizing film, support film, compensation film, and optical clear adhesives between the layers. The key functional layer is the iodine-doped polyvinyl alcohol (PVA) film. The processing of polarizers involves the synthesis of an optical-grade PVA resin, followed by the preparation of highly oriented iodine-doped PVA films, which includes the film casting, iodine doping, boric acid crosslinking, and post-stretching steps. Revealing the multi-scale structure and changes in chain dynamics during processing is crucial for establishing the structure-process-property relationship of PVA-based polarizers. The current work reviews the recent research progress in this direction, primarily including the following: (1) primary chemical structure of PVA, (2) solution casting of PVA films, (3) hierarchical structure and dynamics heterogeneity of plasticized PVA films, (4) formation mechanism of PVA-iodine complexes, and (5) crosslinking mechanism of boric acid in PVA.