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.

Automated summary

This study demonstrates that using 4-dodecylbenzene sulfonic acid (DBSA) as a surface ligand for CsPbBr3 perovskite nanocrystals (PeNCs) can reduce the trap state density, improve the photoluminescence quantum yield, increase the yield production, and enhance the stability compared to conventional octanoic acid (OTAc) capped PeNCs. PeLEDs based on DBSA-PeNCs achieve a higher external quantum efficiency (EQE) and maximum luminance compared to OTAc-PeNCs based PeLEDs. Therefore, introducing DBSA as a surface ligand is an effective way to realize highly efficient PeLEDs.