Organic-inorganic hybrid photochromic materials have been considered one of the most promising photochromic candidates for light detection and information anti-counterfeiting. However, challenges still exist, such as single-color variation, long decoloration time, and lack of in-depth understanding of the photochromic mechanism. Here, a three-component photochromic composite system was designed, composed of two polymer matrices (electron donors) and phosphotungstic acid. By adjusting the ratio of one electron donor, the composite can initiate color change from transparent to deep blue, near-colorless, light mauve, mauve, and grey mauve, respectively, upon UV light irradiation, which has never been reported. These composites also feature flexibility, mechanical robustness, high transparency, faster photochromic reversibility, as well as dispensing printing. Importantly, the underlying multi-color photochromic mechanism is elucidated by leveraging the theoretical simulation and characterization techniques. A UV detection bracelet for real-time UV monitoring and a proton conductor for a wearable biomechanical energy harvester were fabricated using the photochromic composites, indicating application potentials for smart wearable electronics. This work introduces a new type of organic-inorganic photochromic composite and explores the photochromic mechanism, which may guide the design of new photochromic systems for future wearable technologies.

中文翻译：

---

用于可穿戴紫外线监测和生物力学能量收集的颜色可调、多功能光致变色复合材料

有机-无机杂化光致变色材料被认为是最有前途的光检测和信息防伪光致变色候选材料之一。但仍存在颜色变化单一、脱色时间长、对光致变色机理缺乏深入了解等挑战。这里，设计了一种三组分光致变色复合体系，由两种聚合物基体（电子供体）和磷钨酸组成。通过调节一种电子给体的比例，该复合材料在紫外光照射下可以分别引发从透明到深蓝色、近无色、浅紫红色、紫红色和灰紫红色的颜色变化，这是从未报道过的。这些复合材料还具有柔韧性、机械强度、高透明度、更快的光致变色可逆性以及点胶印刷等特点。重要的是，通过利用理论模拟和表征技术阐明了潜在的多色光致变色机制。使用光致变色复合材料制造了用于实时紫外线监测的紫外线检测手环和用于可穿戴生物机械能量采集器的质子导体，表明了智能可穿戴电子产品的应用潜力。这项工作介绍了一种新型有机-无机光致变色复合材料并探索了光致变色机理，这可以指导未来可穿戴技术的新型光致变色系统的设计。