Combinatorial exploration of thermochromic thin films in V-M1-M2-O systems

该项目致力于在V-M1-M2-O系统(M1，M2：例如W，Mg，Er，Li)中探索VO2基热致变色薄膜，以用于未来的智能窗户。待开发的薄膜将在室温附近发生可逆相变，表现出高透光率(Tlum)和太阳辐射调制(Δ)。添加第三元素可以降低VO2基相的转变温度(Tlum)，并改善其热致变色性能(Tlum和ΔTsol)：例如，W可以有效地降低VO2相的Tlum(68℃)，但Tlum和ΔTsol恶化；碱金属和稀土金属改善Tlum，但不显著降低Tc值。因此，需要探索多维搜索空间，以确定满足所有必要要求的新的多维材料。因此，为了获得用于智能窗的VO2基薄膜的更好的性能，首先，将研究具有未开发的M1元素的V-M1-O系统，以寻找降低Tc和改善Tlum的元素。然后，将探索四元体系(V-M1-M2-O)：M1和M2有望对VO2的热致变色性能产生协同作用，以实现更低的T_c和更高的Tlum。这需要一个庞大的实验数据集，这将通过组合材料库的合成及其高通量表征来完成。为了进一步增强Tlum，还将通过掠角沉积将最好的系统制备成纳米多孔薄膜，并将应用保护性减反射膜来进一步优化Tlum。

This project addresses the exploration of VO2-based thermochromic thin films in V-M1-M2-O systems (M1, M2: e.g. W, Mg, Er, Li) for future application in smart windows. Films to be developed will show high luminous transmittance (Tlum) and solar irradiation modulation (ΔTsol) upon a reversible phase transformation around room temperature. Addition of third elements can decrease the transition temperature (Tc) and improve the thermochromic performance (Tlum and ΔTsol) of VO2-based phases: e.g. W can effectively decrease Tc of VO2 (68°C), but Tlum and ΔTsol are deteriorated; alkaline and rare-earth metals improve Tlum but do not lower substantially Tc. Therefore, a multidimensional search space needs to be explored in order to identify a new multinary material which fulfils all necessary requirements. Thus, to achieve better performance of VO2-based thin films for smart windows, first, V-M1-O systems with unexplored elements for M1 will be investigated in search for elements which reduce Tc and improve Tlum. Then, quaternary systems (V-M1-M2-O) will be explored: synergistic effects of M1 and M2 on the thermochromic properties of VO2 are expected, to achieve lower Tc and higher Tlum. This needs a large experimental dataset which will be accomplished by synthesis of combinatorial materials libraries and their high-throughput characterization. The best identified systems will additionally be fabricated as nanoporous films by glancing angle deposition in order to further enhance Tlum, and a protective antireflective coating will be applied to further optimize Tlum.