<p>There are still technique hurdles that needed to be
overcome in the commercialization of electrochromic devices (ECDs) for energy-saving
smart windows. Among them, the long-term stability of ECDs and the high fabrication
cost are <a>the critical issues</a>. The pricey ECDs can only
be paid off through saving the energy for years, and their price will be
dramatically lower if they can be solution-processed. Here, we studied the ions
behaviors in the open-circuit state of electrochromic conjugated polymers
(ECPs) which is important to the stability of ECDs during the operation. Moreover,
we investigated the solution-processable ion storage layers and paired them with
p-type ECPs and demonstrated the possibility of using them in the highly
efficient roll-to-roll fabrication of ECD.</p>
<p>The crosslinkable non-color changing nitroxy
radical-based polymer was investigated as the ion storage layer. With the
applied of crosslinking strategy, the dissolution problems of radical
polymers-based counter electrode in the electrolyte was suppressed, resulting
in the enhancement of both performance and cycling stability of ECDs. Although p-type
ion storage materials are widely studied as the ion storage layers for ECPs,
they need to go through complicated pretreatment processes, including
pre-oxidation, washing, and drying, before they can be paired with ECPs in an
ECD. This complicated process greatly increases the fabrication cost. </p>
<p>In our last work, we applied the UV ozone (UVO)
pretreatment to the solution-processed n-type niobium oxide and evaluated its
potentials to be used as the ion storage layer for p-type ECPs. The UVO
pretreatment generates strong oxidants like ozone or atomic oxygen which induce
the photolysis of organic residues of ligands and organic solvent trapped in
the solution-processed metal oxide layer led to the formation of free radical
species. These highly reactive species promoted the formation of the amorphous
metalâoxygen network. Following by low-temperature annealing (< 150 <sup>o</sup>C),
the ion-storage properties of niobium oxide is comparable with the high
temperature annealed (300 <sup>o</sup>C) niobium oxide. The method is
successfully applied to fabricate niobium oxide on a flexible conductive
substrate and demonstrate the capability to pair with p-type ECPs and fabricate
high-performance ECDs without the need of any pretreatments. The low-temperature solution processing of both
layers will significantly reduce the fabrication cost of ECDs. </p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/10007270 |
| Date | 30 October 2019 |
| Creators | Jiazhi He (7384412) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY-NC-SA 4.0 |
| Relation | https://figshare.com/articles/Electrochromism_and_Solution-Processed_Polymer_Electrochromic_Devices/10007270 |
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