Operando Raman and UV-Vis spectroscopic investigation of the coloring and bleaching mechanism of self-powered photochromic devices for smart windows

Chun, So Yeon; Park, Sunghyeok; Lee, Seok In; Nguyen, Hieu Dinh; Lee, Kyungkoo; Hong, Suk In; Han, Chi Hwan; Cho, Minhaeng; Choi, Han Kyu; Kwak, Kyungwon

doi:10.1016/j.nanoen.2020.105721

“…The merging of the two peaks indicates an increase in symmetry of the tungsten octahedra with lithium intercalation, as the two peak structure is a result of the differing O-W-O bond lengths in the different crystallographic directions. 41,42 In addition to this, the lower frequency Raman peak corresponding to the δ(O-W-O) mode decreases in intensity and broadens. The last major difference is in the higher energy peaks related to the ν(W=O) modes.…”

Section: Resultsmentioning

confidence: 95%

Site-selective ion intercalation controls spectral response in electrochromic hexagonal tungsten oxide nanocrystals

Zydlewski

¹

,

Lu

²

,

Celio

³

et al. 2022

Preprint

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The electrochromism of tungsten oxide occurs through electrochemical reduction, providing active solar control to smart windows, but control over the spectral response is limited and largely empirical. To determine how specific chemical changes result in the optical absorption processes responsible for coloration, we pair structurally well-defined electrochromic nanocrystals (NCs) with cations of varying ionic radii to limit intercalation into specific crystallographic sites. The localized surface plasmon absorption of hexagonal cesium-doped tungsten oxide (Cs:WO3) NCs is enhanced, and new absorption features appear, depending on how the cations intercalate into various interstitial voids. These differences were rationalized using X-ray photoelectron and Raman spectroscopies to reveal the chemical and structural changes leading to the observed variations in the electrochemically induced absorption spectra. Smaller cations, Na+ and Li+, can access additional interstitial sites, leading to a secondary, polaronic mechanism of electrochromism, accounting for enhanced visible light absorption.

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“…These modes correspond to lattice modes, δ(O-W-O), ν(O-W-O), and ν(W=O), respectively. 42,43 The most prominent differences between the reduced and pristine films occur in the ν(O-W-O) modes located between 650-800 cm -1 . For the Li + intercalated film, there are significant changes to the peaks corresponding to this mode, with the two peak structure present in the pristine sample merging into one broad peak.…”

Section: Resultsmentioning

confidence: 99%

Site-selective ion intercalation controls spectral response in electrochromic hexagonal tungsten oxide nanocrystals

Zydlewski

¹

,

Lu

²

,

Celio

³

et al. 2022

Preprint

1

0

View full text Add to dashboard Cite

The electrochromism of tungsten oxide occurs through electrochemical reduction, providing active solar control to smart windows, but control over the spectral response is limited and largely empirical. To determine how specific chemical changes result in the optical absorption processes responsible for coloration, we pair structurally well-defined electrochromic nanocrystals (NCs) with cations of varying ionic radii to limit intercalation into specific crystallographic sites. The localized surface plasmon absorption of hexagonal cesium-doped tungsten oxide (Cs:WO3) NCs is enhanced, and new absorption features appear, depending on how the cations intercalate into various interstitial voids. These differences were rationalized using X-ray photoelectron and Raman spectroscopies to reveal the chemical and structural changes leading to the observed variations in the electrochemically induced absorption spectra. Smaller cations, Na+ and Li+, can access additional interstitial sites, leading to a secondary, polaronic mechanism of electrochromism, accounting for enhanced visible light absorption.

show abstract

“…These modes correspond to lattice modes, δ(O−W−O), ν(O−W−O), and ν(WO), respectively. 47,48 The most prominent differences between the reduced and pristine films occur in the ν(O−W−O) modes located between 650 and 800 cm −1 . For the Li + intercalated film, there are significant changes to the peaks corresponding to this mode, with the two peak structure present in the pristine sample merging into one broad peak.…”

Section: Table 1 Xps Fitting Parameters For Films Electrochemically R...mentioning

confidence: 99%

Site-Selective Ion Intercalation Controls Spectral Response in Electrochromic Hexagonal Tungsten Oxide Nanocrystals

Zydlewski

¹

,

Lu

²

,

Celio

³

et al. 2022

View full text Add to dashboard Cite

The electrochromism of tungsten oxide occurs through electrochemical reduction, providing active solar control to smart windows, but control over the spectral response is limited and largely empirical. To determine how specific chemical changes result in the optical absorption processes responsible for coloration, we pair structurally well-defined electrochromic nanocrystals (NCs) with cations of varying ionic radii to limit intercalation into specific crystallographic sites. The localized surface plasmon absorption of hexagonal cesium-doped tungsten oxide (Cs:WO3) NCs is enhanced, and new absorption features appear, depending on how the cations intercalate into various interstitial voids. These differences were rationalized using X-ray photoelectron and Raman spectroscopies to reveal the chemical and structural changes leading to the observed variations in the electrochemically induced absorption spectra. Smaller cations, Na+ and Li+, can access additional interstitial sites, leading to a secondary, polaronic mechanism of electrochromism, accounting for enhanced visible light absorption.

show abstract

Operando Raman and UV-Vis spectroscopic investigation of the coloring and bleaching mechanism of self-powered photochromic devices for smart windows

Cited by 45 publications

References 51 publications

Site-selective ion intercalation controls spectral response in electrochromic hexagonal tungsten oxide nanocrystals

Site-selective ion intercalation controls spectral response in electrochromic hexagonal tungsten oxide nanocrystals

Site-selective ion intercalation controls spectral response in electrochromic hexagonal tungsten oxide nanocrystals

Site-Selective Ion Intercalation Controls Spectral Response in Electrochromic Hexagonal Tungsten Oxide Nanocrystals

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