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In this study, a WO 3 film with controllable crystallinity has been prepared by radio frequency magnetron sputtering. The WO 3 film with about 400 nm thickness and controllable crystallinity not only has the advantages of amorphous WO 3 with large transmittance modulation and short switching response time but also has the outstanding cyclic stability of crystalline WO 3 . Therefore, this WO 3 film exhibits superior electrochromic performances including large transmittance modulation in the near infrared regime (72.5% at λ = 1000 nm), short coloration/bleaching switching response time (5.3 s for coloration and 3.0 s for bleaching), high coloration efficiency at λ = 1000 nm (80.5 cm 2 C −1 ), and excellent cycle stability. The strategy of preparing a WO 3 film with controllable crystallinity by a simple magnetron sputtering method presents an innovative direction to obtain high-performance WO 3 electrochromic materials applied in the fields of smart windows, spacecraft thermal control, and infrared camouflage.

Colloidal photonic crystal (PC)-based anti-counterfeiting materials have been widely studied due to their inimitable structural colors and tunable photonic band gaps (PBGs) as well as their convenient identification methods. In this review, we summarize recent developments of colloidal PCs in the field of anti-counterfeiting from aspects of security strategies, design, and fabrication principles, and identification means. Firstly, an overview of the strategies for constructing PC anti-counterfeiting materials composed of variable color PC patterns, invisible PC prints, and several other PC anti-counterfeiting materials is presented. Then, the synthesis methods, working principles, security level, and specific identification means of these three types of PC materials are discussed in detail. Finally, the summary of strengths and challenges, as well as development prospects in the attractive research field, are presented.

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