The precursor, a CsPb(Br0.84Cl0.16)3 solution using a custom solvent blend, was blade-coating onto a substrate where the substance crystallised into grains – halide amine additives controlled he growth of perovskite grains and passivate the traps.
“They partially replaced dimethyl sulfoxide with dimethylformamide to obtain a more volatile and supersaturated perovskite precursor solution,” according to the academy. “Perovskite crystal nucleus will precipitate directly from inside of the supersaturated solution in the process of blade-coating, which can effectively increase the density of the nucleus and accelerate the process of nucleation, crystallization, and film-forming, to prepare uniform perovskite films with small grains.”
Film quality was good enough to produce a 28cm2 device with uniform emission and 10.3% peak external quantum efficiency at 489nm.
The work is published as: ‘Large-area and efficient sky-blue perovskite light-emitting diodes via blade-coating‘ in Advanced materials – abstract only available without payment.