All-Inorganic Perovskite Quantum Dots Based on InX3-Trioctylphosphine Oxide Hybrid Passivation Strategies for High-Performance and Full-Colored Light-Emitting Diodes

All-inorganic perovskite quantum dot (PeQD) light-emitting diodes (QLEDs) are promising candidates for the next-generation flat-panel displays and semiconductor lighting technology. However, the stability issues severely limit their commercial applications. In this study, highly stable CsPbX3 (X = CI, Br, I) PeQD films were prepared using InX3 (X = CI, Br, I) and trioctylphosphine oxide (TOPO) as inorganic-organic hybrid ligands to passivate the surface defects of PeQDs. The obtained InX3-TOPO-CsPbX3 PeQDs not only have high photoluminance quantum yields (PL QYs) and very narrow emission (14-35 nm) but also possess long-term stability. This is mainly due to the synergistic effect of InX3 and TOPO inorganic- organic surface ligand passivation, which can effectively inhibit the halogen vacancy and reduce the surface defect of PeQDs. In addition, the chemical states of InBr3-TOPO-CsPbBr3 PeQDs were analyzed by XPS technology and it was found that InX3-TOPO synergistic surface passivation can effectively reduce the Pb=O bond in the crystal lattice. Moreover, full-colored perovskite QLEDs based on InX3-TOPO-CsPbX3 PeQDs were achieved by using ZnO/PBD as the double electron transport layer, NiO/TFB as the double hole transport material, and InX3-TOPO-CsPbX3 PeQDs as the light-emitting layer. The EQE (%) and luminance (cd m(-2)) of red, green, and blue QLEDs based on these InX3-TOPO-CsPbX3 PeQDs were 8.2% and 9080 cd m(-2), 7.8% and 18,600 cd m(-2), and 1.62% and 164 cd m(-2), respectively. This cooperative effect based on the InX3-TOPO hybrid passivation strategy will open a way for the preparation of highly efficient, stable, and color-tunable perovskite QLEDs.