EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

All inorganic perovskite CsPbBr3 nanowires (NWs) have shown excellent performance in various optoelectronic applications such as laser, LED, and photodetection. There have been many studies reported for the growth of CsPbBr3 NWs arrays. However, there NWs are horizontal and cannot be used for devices requiring vertical photon or electron transportation. So far, studies on vertically aligned CsPbBr3 NWs arrays are limited.
Here, we report a low temperature solution growth of vertically aligned CsPbBr3 NWs arrays with excellent stability, using anodized aluminum oxide (AAO) templates. AAO template is commonly used for nanocrystals synthesis, and it has also been used for perovskite nanocrystals synthesis. However, the growth behavior and mechanism of micrometer length CsPbBr3 NWs in AAO from a solution precursor have not been clearly investigated.
In this work, the growth behavior of CsPbBr3 NWs in 5 μm thick AAO template from solution is clearly elucidated. Owing to the low concentration of precursor, the growth of micrometer length pure phase CsPbBr3 NWs in AAO is different from the common way used for growing other perovskite NWs such as MAPbI3. The low solubility of its precursors makes it more challenging to fill the nanopores with CsPbBr3, but it can be overcome by supplying sufficient solution as shown by our results. The NW diameter (10-250 nm) and the length (tens of nm to few μm) can be independently controlled. With decreasing diameter, the CsPbBr3 NWs show a gradual PL blue-shift and crystal structure change from orthorhombic to cubic phase. This is the first observation of physical confinement induced phase transition for CsPbBr3. The physical confinement of AAO also gives the CsPbBr3 NWs a long term air storage stability and good resistance to X-ray exposure. Our results are significant for the growth and and optoelectronic applications of vertical perovskite NWs arrays.