卤素钙钛矿单晶薄片的可控制备、界面调控及光电催化甲氧基呋喃合成研究

Halide perovskites have emerged as promising material for applications in optoelectronics. However, inherent poor stability of perovskite polycrystalline films is the main impediment preventing their performance in photoelectrocatalysis. This research proposal aims at exploiting perovskite single crystal films, which are free of grain boundaries, possessing good stability and band gap alignment by spatial limited reverse temperature crystallization or vapor-phase epitaxial growth technique, including organic-inorganic perovskite (FAPbBr3, MAPbBrxI3-x, FAxMA1-xPbI3) and all inorganic perovskite (CsPbBr3, CsPbIXBr3-x, Cs2SnI6, Cs2TiBr6). The stability of perovskite will be further enhanced by atomic layer deposition or photoinduced deposition technic, so as to achieve photoelectrocatalytic synthesis of methoxy furan, an important organic intermediate, with reasonable performance. Their fundamental properties, film forming process and interfacial modifications will be systematically examined with advanced characterization techniques. Further, uncovering the mechanism and photocatalytic activity of perovskite single crystal films help to reveal high performance and good stability in the field of photoelectrocatlysis.

近年来卤化物钙钛矿在光电器件研究领域中已取得了迅速的发展。然而多晶钙钛矿薄膜受限于较差的稳定性，所以其在光电催化中的研究仍面临巨大挑战。针对这一关键科学问题，本项目拟利用空间限域反温度结晶/气相外延生长法在导电基底原位制备无晶界、稳定性好、带隙可调的钙钛矿单晶薄片（有机无机：FAPbBr3、MAPbBrxI3-x、FAxMA1-xPbI3；全无机：CsPbBr3、CsPbIXBr3-x、Cs2SnI6、Cs2TiBr6）。进一步采用原子层沉积或光诱导沉积技术在钙钛矿薄膜表面沉积金属氧化物和导电聚合物纳米涂层以提高钙钛矿的稳定性，并将其用于重要有机中间体甲氧基呋喃的光电催化合成。在此基础上，对材料的物理化学性质、成膜方法、界面修饰及光电催化性能及机理进行系统研究。揭示其中的规律，推动高效稳定卤素钙钛矿单晶薄片在光电催化领域的发展。

钙钛矿单晶具有的优异光电性能，稳定性好。然而，常规的体相钙钛矿单晶厚度（毫米级）远远大于其载流子扩散长度，这将导致载流发生严重的复合，从而限制其在相关领域的发展。为了获得理想的光电性能，单晶减薄成为提高单晶钙钛矿光电性能的有效策略。在本课题中，我们发展了单晶薄膜制备技术，实现对多种钙钛矿单晶（MAPbBr3、Cs3Bi2I9等）厚度的精准调控。我们还另辟蹊径地将钙钛矿单晶薄片应用于光电催化反应中，拓宽了其传统的应用范畴。将MAPbBr3单晶薄片作为光阳极，成功实现重要有机中间体2,5-二甲氧基-2,5-二氢呋喃的绿色制备。单晶表面经超薄Al2O3钝化处理，以及兼具保护及催化作用的Ti功能层的添加，MAPbBr3/Al2O3/Ti复合光电极表现出了优异的光电性能及稳定性，其法拉第效率高达93%。相关成果已经在Nat. Commun.、J. Am. Chem. Soc.、Adv. Funct. Mater.等国际期刊上发表。