全球变暖和气候变化正日益威胁着人类的生存,为此,许多政府已经制定了“碳达峰”和“碳中和”的“双碳”目标,以减少碳排放。建筑是碳排放的主要来源之一,其能耗占总能耗的四分之一以上。其中,通过门窗的能量损失占一半以上,特别是在透明玻璃窗占比极大的现代建筑中,因为透射阳光会产生很多热量。由于太阳光中的近红外部分是辐射热的主要来源,因而屏蔽近红外光可以有效降低室内温度,助力缓解能源危机。
针对上述问题,北京科技大学杨槐/于美娜团队等人设计了一种基于聚合物分散液晶(PDLC)复合材料的柔性双功能智能窗户,集成银纳米线作为透明导电电极(TCE),以Tm3+/Yb3+-CsxWO3(Tm3+/Yb3+-CWO)作为近红外屏蔽和空气净化层。该智能窗户不但可以通过外加电压的大小控制对可见光和近红外光的透射率以实现太阳光的动态调控,还具有一定的自清洁能力。相关工作以“A novel dual-functional flexible dimming film for smart window applications: energy saving and self-cleaning performance”为题发表于Chemical Engineering Journal,北京科技大学新材料技术研究院张作为为文章第一作者,北京科技大学/北京大学杨槐教授、北京科技大学于美娜特聘副研究员和刘传宝副教授为共同通讯作者。
文章要点
1. 成功制备合成了Tm3+/Yb3+-CWO纳米粒子
Figure 1. (a) UC emission spectra of CWO-0.1/5, 0.3/5, 0.5/5 and 0.7/5; (b) photographs of UC emission; (c) energy level diagram of Tm3+ and Yb3+ ions and the UC process; (d) fluorescence lifetime curve; (e) Photocurrent diagram of different particles; (f) infrared thermal images of samples CWO, CWO-0.1/5 and CWO-0.5/5 under the infrared light; (g) transmission spectra of films coated with CWO, CWO-0.1/5, CWO-0.3/5, CWO-0.5/5 and CWO-0.7/5, respectively; (h) photographs of the PDLC coated with different films; (i) transmission spectra of films coated with 0.1C, 0.3C, 0.5C and 0.7C -0.5/5, respectively.
2. 制备PDLC/Tm3+/Yb3+-CWO 复合薄膜
Figure2. (a) Schematic diagram of the structure of PDLC film; (b-c) longitudinal and cross-sectional images of the polymer matrix in PDLC layer; (d) The electro-optical response of the initial PDLC film and the PDLC coated with Tm3+/Yb3+-CWO layer; inset: response time curve of film; (e) photographs showing the appearance variation of the composite PDLC under different voltages; (f) transmission spectra of composite PDLC under different voltages.
3. 智能窗构建
Figure 3. (a) Schematic diagram of smart windows based on composite PDLC and its working mechanism; (b) schematic working principle of the smart window; (c) photos of the smart window at different voltage. Concentration of CWO-0.5/5 in four window samples: (I) CWO-0.5/5 = 0g/ml, (II) CWO-0.5/5 = 0.011g/ml, (III) CWO-0.5/5 = 0.005g/ml, (IV) CWO-0.5/5 = 0.007g/ml;
4. 结论
原文链接:https://doi.org/10.1016/j.cej.2024.150601
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