有机-无机杂化的铁电材料的设计及其在光伏和光解水上的应用

Ferroelectric materials have a built-in electric field because of the presence of spontaneous polarization. When they are subjected to light, the generated electrons and holes can be separated spontaneously. The separation of electron and hole is also the key process in photovoltaics and photocatalytic water splitting. This characteristics of ferroelectric materials makes it suitable for application in photovoltaics or photocatalytic water splitting. The use of traditional inorganic ferroelectric materials in these areas is still insufficient due to wide band gap, poor absorption of light, and so on. Given the richness of organic-inorganic hybrid compounds, and the tunability in structures and properties (such as bandwidth, light absorption properties), it is possible to develop new photovoltaic and photocatalytic material model by application of these materials to these fields. Therefore, we plan to carry out the design of organic - inorganic hybrid ferroelectric materials and the study of their application in photovoltaics and photocatalytic water splitting. Combined with our previous experience in the study of photovoltaic properties of hybrid ferroelectric materials, it is expected to develop materials for photovoltaics and photocatalytic water splitting by tuning the ferroelectric properties, semiconductor properties and light absorption performance of these materials by means of chemical methods.

铁电材料由于存在自发极化而具有内建的电场。当受到光照射时，产生的电子和空穴可以自发的分离。电子和空穴的分离是光伏和光催化分解水中最重要的一环。 铁电材料的这个特点使得它适合用于光伏或光解水上。传统的无机铁电材料由于在吸光性，带宽等方面的限制，它们在这些方面的应用还很不足。鉴于有机无机杂化化合物种类多，结构和性能（如带宽，吸光性能）都有很大的调节空间，把这些材料的铁电性应用到光伏和光解水上，有可能发展新型的光伏和光催化材料。因此，我们拟开展有机-无机杂化的铁电材料的设计及其在光伏和光解水上的应用的研究。 结合我们过去研究杂化的铁电材料的光伏性质方面的经验，我们相信， 通过化学手段系统调节这类材料的铁电性质、半导体性质以及吸光性能等，有望发展新型的光伏和光解水催化材料。

铁电材料是一种多功能材料，有着广泛的应用。其中，在光伏和光解水等方面的潜在应用有着非常大的优势。这是因为光铁电体中光生电子空穴对可以被自发极化产生的内建电场自动分离。铁电材料主要是钙钛矿氧化物，带宽比较宽，和太阳能光谱不匹配，能量转化效率低，没有能够产生实际的应用。有机-无机杂化的材料很容易实现低的带宽。因此，杂化的铁电半导体有着重要的研究价值。我们以实现半导体铁电性、认识其铁电机理、调控其铁电性能、发掘其光性能为目标，综合运用热分析和变温X－射线单晶衍射分析，以及介电、铁电、二阶非线性光学、热释电等手段进行了系统的结构相变的寻找、铁电性能的表征、光响应特性的表征，发现了一些结构和机理新颖的铁电体，包括多极轴铁电体，无金属钙钛矿铁电体，反常旋光铁电体，稀土发光铁电体等。有的表现了优异的铁电性能，接近钛酸钡的高的相变温度和大的自发极化。这些材料在铁电薄膜，柔性器件，铁电光学开关，铁电发光器件，铁电介电分子识别等领域都有着潜在的应用价值。特别是(2-(ammoniomethyl)pyridinium)SbI5是一个高温的半导体铁电体，相变温度360K,带宽约2.03eV，比经典的光铁电体BiFeO3还低，具有显著的光响应，有望实现光伏和光解水的性能。