Chiral superfluorescence from perovskite superlattices at room temperature

Synthesis of achiral and chiral quasi-2D perovskite superlattices Chemicals Hydroiodic acid (Sigma Aldrich, 57% w/w in H 2 O, 99.9%), hypophosphorous acid (Avra, 50% w/w H 2 O), R -(+)-α-methyl benzylamine (RMBA, Sigma Aldrich, 99%) and S -(−)-α-methylbenzylamine (SMBA, Sigma Aldrich, 99%) were used. Synthesis of MAPbBr 3 single-crystal substrate A stoichiometric mixture of MABr (1 mmol) and PbBr 2 (1 mmol) was dissolved in dimethylformamide (DMF) at room temperature. The solution was filtered through a 0.1-μm polytetrafluoroethylene (PTFE) membrane filter. High-quality MAPbBr 3 single crystals were grown using inverse temperature crystallization by maintaining the filtered solution at 60 °C in an oven. Synthesis of chiral (S/R)MBA ligands In a 100-ml three-necked round-bottom flask cooled in an ice bath, (S/R)MBA (39 mmol, 5 ml) were mixed with anhydrous ethanol (15 ml). Hydrochloric acid (6.6 ml, 58 mmol) was added dropwise under vigorous stirring, and the reaction mixture was stirred overnight. The solution was then heated to 80 °C for 30 min to evaporate the solvent completely. The resulting yellowish residue was dissolved in hot ethanol (5 ml) and refrigerated for 24 h to induce recrystallization. The obtained crystals were washed repeatedly with diethyl ether until colourless, then vacuum-dried overnight to yield white (S/R)MBA crystals. …