Improvement of photoluminescence intensity and film morphology of perovskite by Ionic liquids additive

Metal halide perovskites have received much attention for their application in light-emitting diodes (LEDs) and solar cells in the past several years. Among them, 2D and quasi-2D perovskite with organic long-chain cations introduced have drawn significant attention. However, while improving wet and thermal stability, as the grain size becomes smaller, more defects introduced at the grain boundary and surface, resulting in the increase of non-radiative recombination is becoming the main problem which should be faced by 2D/quasi-2D perovskite materials. Here, we report a new strategy employing ionic liquid named 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(EMB).By adding a small amount of ionic liquid to the precursor, the defect was effectively passivated and the photoluminescence intensity was increased by 11 times and the fluorescent lifetime was increased by about 1.5 times. The flatness of the prepared perovskite thin films has also been effectively improved.