Influence of Crystalline and Shape Anisotropy on Electrochromic Modulation in Doped Semiconductor Nanocrystals

Heo, Sungyeon; Cho, Shin Hum; Dahlman, Clayton J.; Agrawal, Ankit; Milliron, Delia J.

doi:10.1021/acsenergylett.0c01236

Cited by 25 publications

(42 citation statements)

References 46 publications

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“…Transition metal oxide nanocrystals have drawn considerable attention as candidate materials for electrochromic smart windows due to their rich tunability through structural control . By applying a colloidal approach, several structural features of the nanocrystals can be precisely controlled, including crystal phase, particle size, morphology, aliovalent dopant concentration, etc. At an atomic level, it was reported for WO 3– x bulk films and nanocrystals that the local structure of the Li insertion sites has an influence on their coloration efficiency and stability. ,, Moreover, it was shown that engineering the surface facets of WO 3– x nanocrystals by structural control can be used as a method to optimize several electrochromic properties .…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, no significant change in the electrochromic spectral range was observed by engineering the Li insertion sites in these materials where a polaronic mechanism dominates. By contrast, in plasmonic transition metal oxide nanocrystals, nanocrystal shape has significant impact on the spectral range of electrochromic response in the nanocrystals. ,, During electrochemical reduction, the injected electrons accompanying Li insertion in metal oxides can be localized to a varying extent. In plasmonic metal oxides the added electrons tend to be delocalized, while in polaronic metal oxides they have been described as localized to a varying degree on the transition metal ions near the inserted Li.…”

Section: Introductionmentioning

confidence: 99%

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Controlling the Shape Anisotropy of Monoclinic Nb₁₂O₂₉ Nanocrystals Enables Tunable Electrochromic Spectral Range

Katyal

Henkelman

et al. 2021

J. Am. Chem. Soc.

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Electrochromic smart windows that modulate the solar transmittance in a wide and selective spectral range can optimize building energy efficiency. However, for conventional materials such as bulk transition metal oxides, the electrochromic spectral range is constrained by their crystal structure with limited tunability. Herein, we report a method to control the shape anisotropy of monoclinic Nb12O29 nanocrystals and obtain a tunable electrochromic spectral range. We demonstrate the synthesis of monoclinic Nb12O29 nanorods (NRs), extending one-dimensionally along the b direction, and monoclinic Nb12O29 nanoplatelets (NPLs), extending two-dimensionally along the b and c directions. Upon electrochemical reduction accompanied by Li insertion, the NR films show increasing absorbance mostly in the near infrared region. In contrast, the NPL films show increasing absorbance in the near infrared region first followed by increasing absorbance in both visible and near infrared regions. To elucidate the influence of shape anisotropy, we used density functional theory to construct the lithiated structures of monoclinic Nb12O29 and in these structures we identified the presence of square planar sites and crystallographic shear sites for Li insertion. By calculating the theoretical spectra of the lithiated structures, we demonstrate that the Li insertion into the square planar sites results in absorption in the near infrared region in both NRs and NPLs due to their extension in the b direction, while the subsequent insertion of Li into the crystallographic shear sites leads to absorption in both visible and near infrared regions, which only occurs in NPLs due to their extension in the c direction.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Controlling the Shape Anisotropy of Monoclinic Nb₁₂O₂₉ Nanocrystals Enables Tunable Electrochromic Spectral Range

Katyal

Henkelman

et al. 2021

J. Am. Chem. Soc.

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“…Electrochromism refers to an inimitable process involving reversible and persistent color change under a small electric field, which is attractive for information display. − Compared with the emissive mode displays such as light-emitting diodes (LED) and liquid crystal displays (LCD), electrochromic displays with simple device structures do not need a continuous power supply to maintain the display content based on the memory effect. − More importantly, with the high optical transparency in the bleached state, electrochromic displays can provide a “see-through” interface between humans and machines. Due to the remarkable features, many innovative research works on electrochromic displays have emerged in the past few years.…”

Section: Introductionmentioning

confidence: 99%

Self-Powered Rewritable Electrochromic Display based on WO_3-x Film with Mechanochemically Synthesized MoO_3–y Nanosheets

Fang

et al. 2021

ACS Appl. Mater. Interfaces

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Electrochromic displays with bistable color states provide a promising means toward transparent human−machine interfaces. However, the need for external power and the weak optical modulation in the visible light region of most electrochromic devices hinder their practical applications in displays. Here we prepare the MoO 3−y /WO 3−x films based on MoO 3−y nanosheets, which show a dark blue color that matches the response of the eye and meets visual comfort standards compared to pure WO 3−x film. By introducing the highly transparent Al 3+ ion hydrogel layer, a convenient electrochromic device driven by the internal chemical potential has been designed. The device based on the MoO 3−y /WO 3−x film exhibits a high optical modulation in the whole visible light range and can operate at self-powered mode with fast response speed and excellent cycle stability. Moreover, we develop an ionic writing board based on the MoO 3−y /WO 3−x film to surmount the fixed display information issue in conventional electrochromic displays. The ionic writing board exhibits excellent visual display quality and realizes arbitrary writing with a self-powered characteristic. This work provides a simple mechanochemical synthesis procedure of MoO 3−y nanosheets and an ingenious design of self-powered electrochromic devices, which will enable the development of next-generation high-performance electrochromic displays.

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“…Plasmonic semiconductor nanocrystals (PSNCs) have become an increasingly important area of research due to their advantages over traditional metallic plasmonic systems that include tunable carrier density via doping, complete transparency in the visible region, and their ability to strongly absorb near and mid-infrared (NIR, MIR) wavelengths. − These unique properties have led to applications in the fields of sensing, − electrochromics, − and catalysis. − For a typical plasmonic system, the plasma frequency ( ω p ) is primarily determined by the total number of free carriers ( n ) and the effective mass ( m* ) of these carriers, as illustrated by the Drude-Lorentz model, where e is the elementary charge of the free carrier and ε 0 is the permittivity of free space . For systems with the same concentration of aliovalent dopant ion, it is expected that the same number of free carriers would be generated.…”

Section: Introductionmentioning

confidence: 99%

Examining the Effect of Dopant Ionic Radius on Plasmonic M:ZnO Nanocrystals (M = Al³⁺, Ga³⁺, In³⁺)

2021

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Understanding the role of dopant deactivation on plasmon frequency and extinction is important for the rational design of plasmonic semiconductor nanocrystals (PSNCs). Aliovalent dopants do not always contribute a free carrier to a localized surface plasmon resonance (LSPR) for many reasons, including the existence of a depletion region, the pinning of carriers at neutral defect sites, or even the formation of a secondary insulating microphase (inclusions) not observable in the powder X-ray diffraction (pXRD). Here, we investigate such possibilities and their role in determining the LSPR frequency of Al-, Ga-, and In-doped ZnO NCs. Elemental analysis, pXRD, and absorption measurements are utilized to examine the impact of dopant incorporation on the resulting properties. Both simple and advanced effective mass Drude models are used to fit the mid-infrared plasmons, while one-electron oxidant chemical titrations are used as an independent measure of the free electron concentrations. The results of these analyses indicate that dopant/host lattice mismatch leads to inefficient carrier generation for aliovalent substitution, potentially due to local spinel-like inclusions. Smaller dopant ions are more likely to incorporate interstitially and form spinel phases, which results in an increased number of pinned carriers. Improved size matching from Al3+ to In3+ results in increased substitution efficiency and subsequently higher free carrier concentrations and LSPR frequencies. Drude model correction factors are calculated for each sample and compared to the literature value for n-ZnO determined via full band structure calculations. Each dopant is shown to have a unique correction factor, further illustrating the effect of differing ionic radii on the resulting LSPR.

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Influence of Crystalline and Shape Anisotropy on Electrochromic Modulation in Doped Semiconductor Nanocrystals

Cited by 25 publications

References 46 publications

Controlling the Shape Anisotropy of Monoclinic Nb₁₂O₂₉ Nanocrystals Enables Tunable Electrochromic Spectral Range

Controlling the Shape Anisotropy of Monoclinic Nb₁₂O₂₉ Nanocrystals Enables Tunable Electrochromic Spectral Range

Self-Powered Rewritable Electrochromic Display based on WO_3-x Film with Mechanochemically Synthesized MoO_3–y Nanosheets

Examining the Effect of Dopant Ionic Radius on Plasmonic M:ZnO Nanocrystals (M = Al³⁺, Ga³⁺, In³⁺)

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Influence of Crystalline and Shape Anisotropy on Electrochromic Modulation in Doped Semiconductor Nanocrystals

Cited by 25 publications

References 46 publications

Controlling the Shape Anisotropy of Monoclinic Nb12O29 Nanocrystals Enables Tunable Electrochromic Spectral Range

Controlling the Shape Anisotropy of Monoclinic Nb12O29 Nanocrystals Enables Tunable Electrochromic Spectral Range

Self-Powered Rewritable Electrochromic Display based on WO3-x Film with Mechanochemically Synthesized MoO3–y Nanosheets

Examining the Effect of Dopant Ionic Radius on Plasmonic M:ZnO Nanocrystals (M = Al3+, Ga3+, In3+)

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Controlling the Shape Anisotropy of Monoclinic Nb₁₂O₂₉ Nanocrystals Enables Tunable Electrochromic Spectral Range

Controlling the Shape Anisotropy of Monoclinic Nb₁₂O₂₉ Nanocrystals Enables Tunable Electrochromic Spectral Range

Self-Powered Rewritable Electrochromic Display based on WO_3-x Film with Mechanochemically Synthesized MoO_3–y Nanosheets

Examining the Effect of Dopant Ionic Radius on Plasmonic M:ZnO Nanocrystals (M = Al³⁺, Ga³⁺, In³⁺)