​​​​Heating, cooling, and lighting in buildings account for 25% of the total energy consumption in human life. If near-infrared (NIR, contributing to heat) and visible (VIS, light) solar radiation through windows can be actively and independently controlled in response to the climate conditions, this enormous energy demand can be significantly reduced. We study the design and fabrication of new NIR shielding materials based on plasmonic doped metal oxide nanocrystals that perform 

ideal solar modulation with low production cost.

Our plasmonic doped metal oxide nanocrystals have enables NIR-selective electrochromism by a reversible switching of their plasmonic light extinction via electrochemical charging and discharging [1,2]. They can also be used to fabricate thin film coatings that are visibly transparent but efficiently blocking the NIR part of sun light [3]. The target wavelength range can be fine-tuned by modifying the nanocrystal matrix, dopants, and shape [4]. We have developed synthesis methods to various species of doped metal oxide nanocrystals such as alkaline and/or vacancy doped tungsten oxides exhibiting intense light absorption well-tuned to match the solar NIR radiation (700~2000 nm) [5, 6]. 
We investigate various strategies to realize a more efficient and independent control of NIR and VIS regions of sun light through windows by optimizing the architecture of the plasmonic nanocrystals and their sol-gel composites within glass or polymer matrices. Furthermore, we develop innovative systems that can harvest the solar energy that are absorbed by the plasmonic nanocrystals into useful energy sources. 

 

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[1] J Kim, G K Ong, Y Wang, G LeBlanc, T E Williams, T M. Mattox, B A Helms, D J Milliron*, “Nanocomposite architecture for rapid, spectrally-selective electrochromic modulation of solar transmittance” Nano Lett. 15, 5574-5579 (2015). [Link]

[2] Y Wang, J Kim (Co-first author), Z Gao, O Zandi, S Heo, P Banerjee, D J Milliron*, “Disentangling photochromism and electrochromism by blocking hole transfer at the electrolyte interface” Chem Mater. 28 (20), 7198-7202 (2016). [Link]

[3] L. Daugas, K. Lahlil, C. Langavant, I. Florea, E. Larquet, H. Henry, J. Kim*, T. Gacoin* “Investigation of LSPR Coupling Effects toward the Rational Design of CsxWO3–δ Based Solar NIR Filtering Coatings” Advanced Functional Materials 33 2212845 (2023). [Link]​​​​

[4] J Kim*, A Agrawal, F Krieg, A Bergerud, D J Milliron*, “The interplay of Shape and Crystalline Anisotropies in Plasmonic Semiconductor Nanocrystals” Nano Letters 16, 3879-3884 (2016)  [Link]​​​

​[5] Y. Cheref, F. Lochon, L. Daugas, C. C-Langavant, E. Larquet, A. Baron, T. Gacoin, J. Kim* “Dual-band LSPR of tungsten bronze nanocrystals tunable over NIR and SWIR ranges” Chemistry of Materials 34 (21), 9795 (2022). [Link]

[6] J. Oh, J. Davis, S. Tusseau-Nenez, M. Plapp, A. Baron, T. Gacoin*, J. Kim* “Continuous anisotropic growth of plasmonic CsxWO3–δ nanocrystals into rods and platelets” under review at ACS Nano [Link]​

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