Preparation and characterization of protonic solid electrolyte applied to a smart window device with high optical modulation

Abstract

Solid electrolytes based on gelatin, cross-linked with formaldehyde and containing different quantities of glycerol, acetic acid and/or hydrochloric acid, with preparation routine modification have been conducted and characterized using X-ray diffraction, mechanical test, impedance spectroscopy and UV–vis spectrophotometry.The x-ray investigation revealed that all the prepared layers are predominantly amorphous and are influenced noticeably by the addition of different quantities of plasticizer as well acids. The tensile, elongation at break and modulus of the prepared membranes are evaluated and discussed. Using impedance spectroscopy, it was found that, the ionic conductivity acquired a maximum value of 1.28×10−5S/cm at 26wt% acetic acid contents, then decreases at higher concentration due to ion pair formation. The optical investigation revealed transmission ≥98% at wavelengths >580nm. Optimized membrane that has both high conductivity, high transparency, mechanical stability and show good adhesion to both counter and working electrodes was successfully applied to an electrochromic smart window device including tungsten and nickel oxides as electrochromic layers. Using cyclic voltammetry (CV), chronoamperometry (CA), and the device performance has been characterized at different working voltages. The device showed reversible blue coloration, high lifetime cyclic stability, and long-term open circuit memory. The coloration efficiency η600 is enhanced reaching a value 38.1cm2/C. Such results indicate that protonic gelatin-based solid electrolyte is a good candidate as ionic conductor layer in EC devices and of technological and commercial interest.