Trap states engineering toward all-inorganic CsPbBr3 perovskite nanocrystals for highly efficient light-emitting diodes

The room-temperature triple-ligand surface engineering strategy demonstrates the advantages of low-cost and high-yield in the preparation of perovskite nanocrystals (PeNCs). However, conventional octanoic acid (OTAc) with short-chain length shows weak binding energy with Pb2+, resulting in higher trap states density and inferior stability of PeNCs. Here, we prepare CsPbBr3 PeNCs capped with 4-dodecylbenzene sulfonic acid (DBSA) to maintain lower trap states density, a higher photoluminescence quantum yield of 91%, larger yield production and better stability compared to OTAc-PeNCs. Consequently, DBSA-PeNCs based PeLEDs with a peak external quantum efficiency (EQE) of 8.95% and a maximum luminance of 4452 cd m−2 are achieved, which constitute about 3-fold and 2-fold enhancement compared to OTAc-PeNCs based PeLEDs, respectively. These results demonstrate that introducing DBSA as the surface ligand is an effective way to realize highly efficient PeLEDs.