Ultrastable Perovskite Nanocrystal with Amplified Spontaneous Emission via Confined in Vertically Aligned Mesoporous Silica

Metal halide perovskite nanocrystals are known for their impressive photoelectric properties. However, their inferior stability and tendency to agglomerate in solution jeopardized perovskite nanocrystal application. To mitigate this issue, a method is developed for filling perovskite precursor into mesoporous silica (MS) films with subsequent thermal sintering to form nanocrystals in a ceramic matrix. The perovskite precursor vapor state was utilized instead of a liquid state or solid one, allowing maximum diffusion ratio into vertically aligned numerous ultrasmall nanopores (≈4 nm) in MS during the thermal sintering process. Then, the annealing step enables the pore to collapse to encapsulate as‐grown perovskite nanocrystal simultaneously. This collapse of the mesoporous structure ensures that the perovskite can be sealed to mitigate the degradation from moisture and oxygen. As a result, a less discernible photoluminescence degradation was observed when the perovskite‐MS thin film is soaked in water. Furthermore, these films demonstrate distinguished thermal stability, benefiting from their unique structure of inorganic silica anchored onto perovskite surfaces. An amplified spontaneous emission signal is monitored in the vertically aligned MS‐coated perovskite film. The encapsulated strategy provides ultrastable and highly emissive perovskite film that fits the technological requirements of potential laser application.