Strong Quantum Confinement and Fast Photoemission Activation in CH₃NH₃PbI₃ Perovskite Nanocrystals Grown within Periodically Mesostructured Films

In this Communication, a synthetic route is demonstrated to obtain stabilized MAPbI₃ nanocrystals embedded in thin metal oxide films that display well‐defined and adjustable quantum confinement effects over a wide range of 0.34 eV. Mesostructured TiO₂ and SiO₂ films displaying an ordered 3D pore network are prepared by evaporation‐induced self‐assembly of a series of organic supramolecular templates in the presence of metal oxide precursors. The pores in the inorganic films obtained after thermal annealing are then used as nanoreactors to synthesize MAPbI₃ crystallites with narrow size distribution and average radius comprised between 1 and 4 nm, depending on the template of choice. Both the static and dynamic photoemission properties of the ensemble display features distinctive of the regime of strong quantum confinement. Photoemission maps demonstrate that the spectral and intensity properties of the luminescence extracted from the perovskite quantum dot loaded films are homogeneous over squared centimeters areas. At variance with their bulk counterparts, constant emission intensity is reached in time scales at least four orders of magnitude shorter.