Growth Of Organic-inorganic Perovskite Single Crystals

Perovskite solar cell has been a hot topic which is drawing significantly broad attention. ABX3 perovskites do not merely possess the ability to transport both holes and electrons, but they can also absorb lights with short wavelengths for its wide band gap. The synthesis of perovskite varies, normally including one-step method, two-step method, dual source thermal evaporation and fast deposition-crystallization, etc, among which, the procedure of fast deposition-crystallization could give us compact and flat perovskite thin film without heating of high temperature. However, for fast deposition-crystallization, there are no systematic investigation on the principles and the controlling conditions. This article has a fine study for the phases of perovskite in the mixed solvent as well as for the phase transformation conditions, taking phase transformation and crystallization principles as the entry point in Fast Deposition-Crystallization method. Beside, we also explored a novel growing method of single crystal perovskites according to the published growing method of a single crystal perovskite. The single crystal perovskites were further exploited for their physicochemical properties. The content is mainly like below:1. Study on the phase transformation of MAPbI3 perovskite. MAPbI3 perovskite could exist in three forms namely solute, perovskite crystal and intermediate product in the mixed solvent of 1,4-Butyrolactone-Chlorobenzene, N,N-Dimethylformamide-Chlorobenzene. The specific existing form would be affected by the combined affection of temperature, solvent ratio and solute ratio. And by heating or varying the ratio of the mixed solvent, the transformation of phases could be achieved.2. The growth of MAPbI3, MAPbBr3, MAPbCl3 perovskite single crystals, and crystal parameters of MAPbI3 perovskite. MAPbI3 perovskite has totally three types of crystal lattices, among which the tetragonal structure exists under room temperature, and the cubic crystal exists under high temperature (above 57℃). When chlorobenzene is added to the growth solution, the growth temperature is lowered and cubic lattice was successfully procured.3. The growth of mixed MAPbIxBr3-x and MAPbBrxCl3-x single crystal perovskites. The relationship was investigated between halogen element ratio and physicochemical properties. Furthermore, we also briefly discussed the factors on the ratio of halogen elements in doped single crystal perovskites.