ИСТИНА

We present a new effective strategy of perovskite films preparation for optoelectronic applications, in particular, solar cells using novel reactant compounds - reactive polyiodide melts and lead precursors. The reactive polyiodide melts (RPM) can be easily obtained from solid I2 and MAI (I2 and FAI), exhibit very low melting points and high chemical activity. Being liquid at room temperature, they alleviate the need to use a solvent for the conversion of metallic lead to perovskite CH3NH3PbI3. Using this innovative approach, we demonstrate that a thin layer of metallic lead can be converted instantly into polycrystalline perovskite films of high electronic quality at room temperature. The reaction between the metallic lead and reactive polyiodide melts proceeds rapidly without solvents or additional agents. Depending on the preparation conditions, two types of morphology are obtained - sphere-like and cubic crystals of perovskite. The latter case gives high quality perovskite films with large crystals exhibiting intense photoluminescence with lifetimes longer than 200 ns. There are several advantages of the proposed method of producing of thin film of lead-halide perovskite. The first one is the use of the thin film of lead as a precursor that can be deposited in a controllable way using a large number of standard techniques such as sputtering, galvanostatic deposition, etc. on different substrates, including flexible ones. Thus the thickness of the perovskite layer can be easily controlled. The second advantage is the speed of conversion that is orders of magnitude higher than can be reached in a two-step approach using CH3NH3I in i-PrOH. We also show that mixed perovskites MAxFA1-xPbI3-xBrx can also be easily obtained using this strategy. In particular, single-phase MA-stabilized FAPbI3 with long charge carriers lifetimes was obtained.