Optimization of GLAD Angle for E-Beam-Fabricated Tungsten Oxide (WO3) Thin Films Towards Novel Electrochromic Behavior

It is hypothesized that increasing the glancing angle deposition (GLAD) will increase the porosity of WO3 thin film, thus allowing for better ion diffusion. However, beyond a certain GLAD angle, the film follows a reverse trend and grows quite dense, which is attributable to the highly inclined columnar structure. Consequently, finding an optimal GLAD angle that can produce a perfect porous WO3 film under the given experimental conditions is critical. In this context, WO3 thin films, each 400 nm thick, are fabricated using e-beam evaporation at GLAD angle alpha = 0 degrees (planar), 30 degrees, 55 degrees, 65 degrees, 70 degrees and 80 degrees on fluorine-doped tin oxide (FTO)-coated substrates and Corning glass substrates. The crystalline structure, surface morphology, optical, electrochemical and electrochromic characteristics of the WO3 thin films are all investigated in detail. Film fabricated at a GLAD angle of 65 degrees showed optimal optical transmittance of 75%, band gap of 3.25 eV, highest coloration efficiency (CE) of 31.06 cm(2)/C and highest diffusion coefficient (D) of 7.215 x 10(-4) cm(2)/s. In conclusion, it may be inferred that the optimal GLAD angle under the current experimental conditions is 65 degrees, which could give an ideally porous WO3 film with novel electrochromic behavior. [GRAPHICS] .

Automated summary

The glancing angle deposition (GLAD) technique is used to fabricate WO3 thin films with varying porosity. It is found that an optimal GLAD angle of 65 degrees is able to produce a porous WO3 film with ideal electrochromic behavior, exhibiting high optical transmittance, band gap, coloration efficiency, and diffusion coefficient.