High‐Efficient Photochromic <scp>P123</scp>/<scp>WO_x</scp> Films via Semi‐Annealing for Enhanced Optical Data Storage

ABSTRACT Tungsten oxide has attracted much attention as a fascinating medium for optical energy transformation due to the significant color‐changing under light irradiation. By now, most of the photochromism enhancement strategies focus on the interaction between the tungsten oxide and its surrounding medium, such as semiconductors or polymers, to promote the spatial separation between electrons and holes in tungsten oxide. However, modulating the intrinsic photochromism of tungsten oxide is rather difficult. Herein, we construct a humidity‐dependent P123/WO x composite film via a semi‐annealing method. The transparency of the film is significantly improved with the decrease of environmental humidity. By setting different annealing temperatures, the photochromic performance can be adjusted from two aspects: the population of oxygen vacancies in WO x and the hydrogen bond ratio in P123/WO x , respectively. Compared to commercial WO 3 films, the P123/WO x film shows an obvious increase in photochromic amplitude, photo‐response speed, and holographic storage efficiency. The hybrid film is also used as a sandwiched layer to construct a polarization multiplexed optical storage, exhibiting the promising advantages in high‐density information storage and photochromism‐adjustable devices.