Rational Design of Oxygen Deficiency-Controlled Tungsten Oxide Electrochromic Films with an Exceptional Memory Effect
Yingdi Shi, Mingjun Sun, Yong Zhang, Jiewu Cui, Xia Shu, Yan Wang, Yongqiang Qin, Jiaqin Liu, Hark Hoe Tan, Yucheng Wu
Abstract
Owing to their nonemissive characteristics, electrochromic materials promise distinct advantages in developing next-generation eye-friendly information displays. Yet, it remains a challenge to manipulate the structure of the materials to achieve a strong memory effect with high optical contrast, which is of importance for displaying images with essentially zero energy consumption. Here, we design a mixed crystalline WOx thin film implanted with massive oxygen deficiencies based on a conventional reactive magnetron sputtering process. The obtained WOx film exhibits high dual-band optical modulation in both visible (VIS, 99.0% in 633 nm) and near-infrared (NIR, 94.2% in 1300 nm) regions as well as an exceptional memory effect (the colored transmittance increases only by 0.04% at 633 nm after 50 days). The enhanced electrochromic performance can be attributed to dense Li+-ion binding sites as well as the trapping effect provided by the massive internal oxygen deficiencies. The strategy in this work bestows the WOx thin film a promising candidate for developing electrochromic information displays and other energy-efficient devices as well.