Complementary ligand decorated cesium lead bromide nanoplatelets for high performance light-emitting diodes

Two dimensional cesium lead bromide (CsPbBr 3 ) nanoplatelets (NPLs) have gained numerous attention due to its tunable thickness, large exciton binding energy and excellent optical properties which can be applied in various photoelectric device. However, synthesizing blue emitting NPLs with long-term stability and high photoluminescence quantum yields (PLQYs) was still difficult. Here, we demonstrate a strategy based on surface ligand engineering, using didodecyldimethylammonium bromide and sodium dodecylbenzene sulfonate as surface ligands to impart higher PLQYs to perovskite materials while improving the stability of CsPbBr 3 NPLs. These ligands strongly interact with CsPbBr 3 NPLs, compared with untreated materials, effectively eliminating defects on the surface of NPLs and significantly improving the structural stability of perovskite materials. High-quality CsPbBr 3 NPLs with high color purity (narrow peaks located at ∼470 nm) and PLQYs up to 90 % were prepared by this method. In addition, the stability of treated NPLs under some harsh environments (including long-term storage, high temperature and 365 nm UV light irradiation) has been significantly improved. White light-emitting diodes were finally fabricated using these highly bright and stable CsPbBr 3 NPLs.