Structure Origin of Polarizer Failure Difference Under Different Aging Conditions

ABSTRACT This study investigates the long‐term stability of iodine‐doped poly(vinyl alcohol) (PVA) polarizers, which are essential optical components in high‐resolution displays such as LCDs and OLEDs. Two industry‐relevant accelerated aging protocols, 65°C/95% relative humidity (RH) and 105°C/0% RH, were compared to assess how different hygrothermal environments affect optical performance, iodine speciation, and microstructure. After 500 h, the sample aged at 105°C retained a polarization efficiency of 99.99%, whereas the sample aged at 65°C/95% RH dropped to 96.86%. Visible color shifts accompanied these changes: hygrothermally aged films turned light blue, while dry‐heat aged films browned. SEM Raman analysis linked these shifts to changes in the I 5 − /I 3 − ratio, which increased by 1.2% under high humidity and decreased by 1.0% under high temperature. Wide‐angle X‐ray scattering (WAXS) revealed sharper azimuthal peaks in aged samples, indicating preserved molecular orientation. Time‐domain 1 H NMR showed a 6% increase in rigid segments, a 9% reduction in semi‐rigid chains, and a 1% drop in mobile fractions under dry heat, reflecting enhanced crystallinity and restricted chain mobility. FTIR spectra confirmed that changes were primarily physical rather than chemical. This comparative analysis highlights distinct degradation pathways under two extreme reliability conditions.