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Elucidating the Crystallite Size Dependence of the Thermochromic Properties of Nanocomposite VO2 Thin Films
ACS Omega ( IF 3.7 ) Pub Date : 2018-10-29 00:00:00 , DOI: 10.1021/acsomega.8b02093 Nathan A. Fleer 1, 2 , Kate E. Pelcher 1, 2 , Kelly Nieto 1, 2 , Erick J. Braham 1, 2 , Jian Zou 3 , Gregory A. Horrocks 1, 2 , Yuki Naoi 4 , Sean W. Depner 5 , Brian J. Schultz 5 , Jun Amano 4 , Diane G. Sellers 1, 2 , Sarbajit Banerjee 1, 2
ACS Omega ( IF 3.7 ) Pub Date : 2018-10-29 00:00:00 , DOI: 10.1021/acsomega.8b02093 Nathan A. Fleer 1, 2 , Kate E. Pelcher 1, 2 , Kelly Nieto 1, 2 , Erick J. Braham 1, 2 , Jian Zou 3 , Gregory A. Horrocks 1, 2 , Yuki Naoi 4 , Sean W. Depner 5 , Brian J. Schultz 5 , Jun Amano 4 , Diane G. Sellers 1, 2 , Sarbajit Banerjee 1, 2
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Fenestration elements that enable spectrally selective dynamic modulation of the near-infrared region of the electromagnetic spectrum are of great interest as a means of decreasing the energy consumption of buildings by adjusting solar heat gain in response to external temperature. The binary vanadium oxide VO2 exhibits a near-room-temperature insulator–metal electronic transition accompanied by a dramatic modulation of the near-infrared transmittance. The low-temperature insulating phase is infrared transparent but blocks infrared transmission upon metallization. There is considerable interest in harnessing the thermochromic modulation afforded by VO2 in nanocomposite thin films. However, to prepare a viable thermochromic film, the visible-light transmittance must be maintained as high as possible while maximizing thermochromic modulation in the near-infrared region of the electromagnetic spectrum, which necessitates the development of high-crystalline-quality VO2 nanocrystals of the optimal particle size embedded within the appropriate host matrix and refractive index matched to the host medium. Here, we demonstrate the preparation of acrylate-based nanocomposite thin films with varying sizes of embedded VO2 nanoparticles. The observed strong size dependence of visible-light transmittance and near-infrared modulation is explicable on the basis of optical simulations. In this article, we elucidate multiple scattering and absorption mechanisms, including Mie scattering, temperature-/phase-variant refractive-index mismatch between VO2 nanocrystals and the encapsulating matrix, and the appearance of a surface plasmon resonance using temperature-variant absorptance and diffuse transmittance spectroscopy measurements performed as a function of particle loading for the different sizes of VO2 nanocrystals. Nanocrystals with dimensions of 44 ± 30 nm show up to >32% near-infrared energy modulation across the near-infrared region of the electromagnetic spectrum while maintaining high visible-light transmission. The results presented here, providing mechanistic elucidation of the size dependence of the different scattering mechanisms, underscore the importance of nanocrystallite dimensions, refractive-index matching, and individualized dispersion of particles within the host matrix for the preparation of viable thermochromic thin films mitigating Mie scattering and differential refractive-index scattering.
中文翻译：
阐明纳米复合VO 2薄膜热致变色性质的微晶尺寸依赖性
作为一种通过响应于外部温度调节太阳热能来减少建筑物能耗的手段，能够对电磁频谱的近红外区域进行光谱选择性动态调制的窗饰元件引起了人们的极大兴趣。二元氧化钒VO 2表现出近室温的绝缘体－金属电子跃迁，并伴随着对近红外透射率的显着调制。低温绝缘相是红外透明的，但在金属化时会阻止红外透射。利用VO 2提供的热致变色调制引起了极大的兴趣在纳米复合薄膜中。然而，为了制备可行的热致变色膜，必须保持可见光透射率尽可能高，同时在电磁光谱的近红外区域中最大化热致变色调制，这需要开发高品质的VO 2纳米晶体。嵌入合适基质基质中的最佳粒径和与基质介质匹配的折射率。在这里，我们演示了具有不同尺寸的嵌入式VO 2的丙烯酸酯基纳米复合薄膜的制备纳米粒子。在光学模拟的基础上，可以观察到可见光透射率和近红外调制的强尺寸依赖性。在本文中，我们阐明了多种散射和吸收机制，包括Mie散射，VO 2纳米晶体与封装基质之间的温度/相变折射率失配以及使用温变吸收率和扩散的表面等离振子共振的出现。对于不同尺寸的VO 2，透射率光谱测量作为颗粒载荷的函数纳米晶体。尺寸为44±30 nm的纳米晶体在电磁光谱的近红外区域显示出高达32％的近红外能量调制，同时保持了高可见光透射率。此处给出的结果提供了对不同散射机理的尺寸依赖性的机理解释，强调了纳米微晶尺寸，折射率匹配以及颗粒在基质中的个性化分散对于制备减轻米氏散射的可行的热致变色薄膜的重要性。和微分折射率散射。
更新日期：2018-10-29
中文翻译：
阐明纳米复合VO 2薄膜热致变色性质的微晶尺寸依赖性
作为一种通过响应于外部温度调节太阳热能来减少建筑物能耗的手段，能够对电磁频谱的近红外区域进行光谱选择性动态调制的窗饰元件引起了人们的极大兴趣。二元氧化钒VO 2表现出近室温的绝缘体－金属电子跃迁，并伴随着对近红外透射率的显着调制。低温绝缘相是红外透明的，但在金属化时会阻止红外透射。利用VO 2提供的热致变色调制引起了极大的兴趣在纳米复合薄膜中。然而，为了制备可行的热致变色膜，必须保持可见光透射率尽可能高，同时在电磁光谱的近红外区域中最大化热致变色调制，这需要开发高品质的VO 2纳米晶体。嵌入合适基质基质中的最佳粒径和与基质介质匹配的折射率。在这里，我们演示了具有不同尺寸的嵌入式VO 2的丙烯酸酯基纳米复合薄膜的制备纳米粒子。在光学模拟的基础上，可以观察到可见光透射率和近红外调制的强尺寸依赖性。在本文中，我们阐明了多种散射和吸收机制，包括Mie散射，VO 2纳米晶体与封装基质之间的温度/相变折射率失配以及使用温变吸收率和扩散的表面等离振子共振的出现。对于不同尺寸的VO 2，透射率光谱测量作为颗粒载荷的函数纳米晶体。尺寸为44±30 nm的纳米晶体在电磁光谱的近红外区域显示出高达32％的近红外能量调制，同时保持了高可见光透射率。此处给出的结果提供了对不同散射机理的尺寸依赖性的机理解释，强调了纳米微晶尺寸，折射率匹配以及颗粒在基质中的个性化分散对于制备减轻米氏散射的可行的热致变色薄膜的重要性。和微分折射率散射。
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