Achieving high-efficiency CsPbBr3 perovskite light emitting diode via GABr- didecyldimethyl ammonium bromide hybrid ligand passivation strategies

Cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite quantum dots (PQDs) have attracted extensive attention due to their high crystal structure stability. However, a large number of defects generally exist on the surface of PQDs, which results in non-radiative recombination and affects the electrical performance of their devices. Here, we report a simple and feasible hybrid ligand passivation strategy to modify PQDs surface defects. Guanidine bromide (GABr) and didecyldimethyl ammonium bromide (DDAB10) were dissolved in toluene to modify the surface trap state of PQDs. The post-treatment strategy effectively inhibits vacancy defects and improves elec-trical performance. The strong affinity (N-H...Br) between guanidine ion and halogen not only reduces the defect density of PQDs, but also improves their carrier mobility. The results also show that the guanidine ion is closely bonded to the surface of PQDs, the fluorescence lifetime is longer, and the defect density is smaller. Finally, a green perovskite light-emitting diode (PeLED) device with an EQE of 10.02% and current efficiency of 36.4 cd/A was obtained.