Fast growth of monocrystalline thin films of 2D layered hybrid perovskite

During the past few years hybrid organic-inorganic perovskites (HOIPs) have attracted much interest as solution-processed semiconductors with high potentialities in optoelectronics and photovoltaics. On the one hand 3D HOIPs such as CH3NH3PbI3 have shown their outstanding performances when incorporated in solar cells. On the other hand their 2D layered counterparts such as (C6H5C2H4NH3)2PbI4 (PEPI) are promising materials for light emitting devices because of their strong emission at room temperature. However, the optoelectronic properties of hybrid perovskite polycrystalline films suffer from a microscale grain structure. In order to take advantage of the great potential of these materials for both photovoltaïcs and emitting devices, the synthesis of large monocrystalline films is a key issue. Here we propose a fast crystallization method for the 2D layered hybrid perovskite PEPI. A vapor-assisted process coupled with a capping of the precursor solution allows to grow 2-dimensionnal thin films with millimetric monocrystalline grains, a high aspect ratio and a good surface quality. Moreover, this growth is several orders of magnitudes faster than the other reported techniques. In addition, we highlight the benefits of using γ-butyrolactone (GBL) for the growth of layered perovskites monocrystalline grains.