Gelatin-based protonic electrolyte for electrochromic windows

Abstract

Proton-conducting gel polymer electrolytes based on gelatin plasticized with glycerol and containing acetic acid were investigated, characterized, and applied to electrochromic window. For glycerol contents varying from 7% to 48%, the conductivity of the uniform and predominantly amorphous gel electrolyte was found to follow a Vogel-Tamman-Fulcher behavior with the temperature. Typically, for the electrolyte chosen to make 7×2 cm 2 electrochromic smart window with the configuration: glass/ fluor-doped tin oxide (FTO)/WO 3 /gelatin electrolyte/CeO 2 -TiO 2 /FTO/glass and containing 28% of glycerol, the conductivities were found to be of the order of 5×10 −5 S/cm at room temperature and 3.6×10 −4 S/cm at 80°C. The device was characterized by spectroelectrochemical techniques and was tested up to 10,000 cycles showing a fast coloring/ bleaching behavior, where the coloring process was achieved in 10 s and the bleaching in 2 s. The transmission variation at the wavelength of 550 nm was about 15%. The cyclic voltammograms showed a very good reversibility of the cathodic/anodic processes, and the charge density was about 3.5 mC/cm 2 . The memory tests showed that the transmittance in the colored state increased by 8% in 90 min after removing the potential.

Prussian blue for electrochromic devices

“…The decrease of Q in charges and the increase of Q out /Q in values is most likely due to ECD degradation over time. However, the charge density values of this ECD are comparable to the results discusses above as well as to -4.8 mC·cm -2 shown by Costa et al [35] for the device with a glass-ITO/WO 3 /starch-Li(ClO 4 )/CeO 2 -TiO 2 /ITO-glass or to the ECD with agar-based electrolyte [33]. This would indicate that the process is not fully reversible.…”

“…The anodic electrochemical response of the ECDs with AgarLiClO 4 and Agar-Eu(pic) 3 membranes was composed by two peaks, where one was large and its maximum was centered in between -0.3 and -0.03 V. The second one was small and centered in between 0.4 and 0.7 V. The presence of this additional oxidation process was probably due to the electrolyte as already observed for ECDs composed of WO 3 /gelatin-glycerol/CeO 2 -TiO 2[33], but different of ECD composed of WO 3 /starch-glycerol/CeO 2 -TiO 2[13].The charge density response measured by chronoamperometry at -3.0 V/+2.0 V; 15 s/15 s, 30 s/30 s and 60 s/60 s steps of ECD containing solid electrolyte based on agar and Eu(CF 3 SO 3 ) 3 is shown inFig. 6a.…”

Ionically conducting Er3+-doped DNA-based biomembranes for electrochromic devices

“…4, reveal that the DNA matrix and the doped samples are predominantly amorphous. The broad Gaussian peak centred at about 21 • in the XRD patterns of these electrolytes is also produced by other systems based on natural macromolecules [20,34]. The diffractogram of DNA 10 Er (Fig.…”

Electrochromic device with Prussian blue and HPC-based electrolyte

“…As it was shown above even though the ECDs have the same Prussian blue EC layer they display quite different electrochemical and spectroscopic performances probably due to the different electrolytes. Therefore, electrolyte is also an important part of an ECD, and among many different polymer electrolytes (SPEs) those based on natural polymers are investigated [14,15]. Besides many different natural macromolecules that were already reported as SPEs the new ones are being developed and described.…”