Influence of single-nanoparticle electrochromic dynamics on the durability and speed of smart windows
Influence of single-nanoparticle electrochromic dynamics on the durability and speed of smart windows
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DOI：
10.1073/pnas.1822007116
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发表时间：
2019-06-25
影响因子：
11.1
通讯作者：
Sambur, Justin B.
中科院分区：
文献类型：
--
作者：
Evans, R. Colby;Ellingworth, Austin;Sambur, Justin B.
纳米材料在提高电致变色智能窗效率、速度和耐用性方面具有巨大潜力。然而，纳米颗粒的尺寸、形状和表面缺陷各不相同，并且纳米颗粒的异质性如何影响颗粒相关的电致变色特性尚不清楚。在这里，我们使用单纳米颗粒级光电成像来测量电致变色氧化钨纳米棒的结构-功能关系。由于锂离子插入光学非活性表面位点，单纳米棒表现出与粒子相关的着色等待时间（从 100 毫秒到 10 秒）。较长的纳米棒比较短的纳米棒颜色更深，并且表现出从纳米棒末端到中间增加的锂离子梯度。粒子相关的离子插入动力学有助于大面积智能窗户上可变的着色速率和幅度。接下来，我们量化了当纳米棒构件组装成薄膜时，颗粒与颗粒之间的相互作用如何影响着色动力学和可逆性。有趣的是，与由相同颗粒制成的薄膜相比，单个颗粒的着色速度快 4 倍，循环可逆性高 20 倍。这些发现使我们能够提出一种纳米结构电极架构，该架构可以优化大面积智能窗户的光学调制率和可逆性。
Nanomaterials have tremendous potential to increase electrochromic smart window efficiency, speed, and durability. However, nanoparticles vary in size, shape, and surface defects, and it is unknown how nanoparticle heterogeneity contributes to particle-dependent electrochromic properties. Here, we use single-nanoparticle-level electro-optical imaging to measure structure-function relationships in electrochromic tungsten oxide nanorods. Single nanorods exhibit a particle-dependent waiting time for tinting (from 100 ms to 10 s) due to Li-ion insertion at optically inactive surface sites. Longer nanorods tint darker than shorter nanorods and exhibit a Li-ion gradient that increases from the nanorod ends to the middle. The particle-dependent ion-insertion kinetics contribute to variable tinting rates and magnitudes across large-area smart windows. Next, we quantified how particle-particle interactions impact tinting dynamics and reversibility as the nanorod building blocks are assembled into a thin film. Interestingly, single particles tint 4 times faster and cycle 20 times more reversibly than thin films made of the same particles. These findings allow us to propose a nanostructured electrode architecture that optimizes optical modulation rates and reversibility across large-area smart windows.