Efficient emission of quasi-two-dimensional perovskite films cast by inkjet printing for pixel-defined matrix light-emitting diodes

Quasi-two-dimensional(quasi-2D)perovskites are promising materials for potential application in light-emitting diodes(LEDs)due to their high exciton binding energy and efficient emission.However,their luminescent performance is limited by the low-n phases that act as quenching luminescence centers.Here,a novel strategy for eliminating low-n phases is proposed based on the doping of strontium bromide(SrBr_(2))in perovskites,in which SrBr_(2)is able to manipulate the growth of quasi-2D perovskites during their formation.It was reasonably inferred that SrBr_(2)readily dissociated strontium ions(Sr^(2+))in dimethyl sulfoxide solvent,and Sr^(2+)was preferentially adsorbed around[PbBr_(6)]^(4−)through strong electrostatic interaction between them,leading to a controllable growth of quasi-2D perovskites by appropriately increasing the formation energy of perovskites.It has been experimentally proved that the growth can almost completely eliminate low-n phases of quasi-2D perovskite films,which exhibited remarkably enhanced photoluminescence.A high electroluminescent efficiency matrix green quasi-2D perovskite-LED(PeLED)with a pixel density of 120 pixels per inch fabricated by inkjet printing technique was achieved,exhibiting a peak external quantum efficiency of 13.9%,which is the most efficient matrix green quasi-2D PeLED so far to our knowledge.