Preparation of WO₃ Films with Controllable Crystallinity for Improved Near-Infrared Electrochromic Performances

Abstract

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.

Thickness Dependence of WO3 and NiOx Thin Films in All‐Solid‐State Complementary Electrochromic Devices

“…Furthermore, more active units could effectively participate in the redox reactions and more ions can be stored in the EC layer during the EC process. [ 29,30 ]…”

Two-dimensional WO3 nanosheets for high-performance electrochromic supercapacitors

“…In addition to these strategies, the electrochromic properties, cycling life, and structural stability of a bifunctional material (such as WO 3 and NiO) are closely related to its crystalline feature and crystallinity. 12 In the literature, [13][14][15][16][17][18][19][20] it has been reported that each crystalline feature and oriented crystal face of the electrode material can show a different opticalelectrochemical performance and cycling stability due to different atomic arrangement and surface energy. For example, Kang et al synthesized (001)-oriented monoclinic nanorod WO 3 films on FTO by a seed-assisted solvothermal and thermal treatment process.…”

Advanced developments in nonstoichiometric tungsten oxides for electrochromic applications

“…8,67 Other recent approaches attempted based on energy savings EC materials and technologies for novel multifunction are published elsewhere. 67,68,[70][71][72][73][74][75][76][77][78] Modern commercial buildings in European countries have installed EC smart windows functioning instead of the active air conditioning, and approximately 4.5% of energy can be saved annually in the USA and Australia. 79 Similarly, the auto-dimming smart glass and automotive rear-view mirrors have been commercialized.…”