Quantitative Assessment of the Cycling Stability of Different Electrochromic Materials and Devices

Abstract

Despite the long-standing history of electrochromism, there is a lack of universally accepted methods for quantitatively comparing cycling stability between different electrochromic materials or devices. By proposing a straightforward three-step procedure, we report a simple set of parameters that describe the cycling stability performance the most frequently used electrochromic materials, namely, conducting polymers, transition metal oxides, metallo-supramolecular polymers, and viologens. The main highlights of this procedure are an adequate definition of the testing conditions and the analytical description of the evolution of the performance of materials through continuous cycling. The resulting parameters allow us, not only to perform comparative studies among different materials and devices but also to identify tendencies, and therefore establish the corresponding balance, between the testing conditions and the cycling stability and/or optical performance obtained. This method constitutes a powerful decision-making tool for the academic and industry-related electrochromic community.

Role of Side-Chain Free Volume on the Electrochemical Behavior of Poly(propylenedioxythiophenes)

“…However, when using a lower dielectric constant electrolyte of tetrabutylammonium hexafluorophosphate, TBA + PF 6 – , dissolved in propylene carbonate, PC, a 35% loss of redox capacity over just 100 cycles was recorded (Figure b). In parallel, a notable decrease in the neutral-state optical density was found (Figure c)not an uncommon phenomenon in many well-studied conducting polymers. ,, …”

“…In parallel, a notable decrease in the neutral-state optical density was found (Figure 1c)�not an uncommon phenomenon in many well-studied conducting polymers. 2,9,10 The example of P(OE3)-P(Me) illustrates the challenge that persists in applying π-conjugated polymer semiconductors, including P(ProDOT)s, at large scale, as many important structure/property interrelations are still ill understood. Specifically, drastic differences in their electrochemical response are reported even for polymers of relatively similar chemical designs and/or when, e.g., changing the electro- lyte.…”

“…In parallel, a notable decrease in the neutral-state optical density was found ( Figure 1 c)—not an uncommon phenomenon in many well-studied conducting polymers. 2 , 9 , 10 …”

Neural Network-Based Digital Camera Spectrophotometer: Application to Chromogenic Technologies Characterization

“…The stability of an electrochromic material is usually quantified by monitoring the transmittance evolution at a certain representative wavelength when the material is subjected to continuous color switching cycles. A recently reported standard method, 55 which proposes the use of the N 80 parameter for stability/degradation quantification, was used in this study. It represents the number of cycles needed to retain 80% of the initial contrast.…”

Film Deposition of Electrochromic Metal Oxides through Spray Coating: A Descriptive Review

“…• the memory effect (i.e., the capacity to maintain a transmittance state without applying an additional charge); • the spectral selectivity (i.e., the ability to selectively control different wavelength ranges of transmittance, typically NIR independently of VIS); • and the cycling stability and durability, characterized by the number of switching cycles during which the optical change can be preserved without significant degradation, being influenced by cycling testing conditions-the bias type and duration, electrolyte nature, temperature and pressure, illumination conditions, etc. To this end, the reader could refer to the recent report of J. Padilla et al [40], presenting a detailed procedure that aims at adequately defining the testing conditions and the analytical description of the evolution of the performance of EC materials through continuous cycling. Their evaluation method relies on three steps: (i) define the reference switching conditions for each material, (ii) define the testing conditions used during the stability test, and (iii) use an analytical description of the contrast vs. the cycling run, like the number of cycles corresponding to an 80% performance retention.…”