Enhancing the Performance of Quasi-Two-Dimensional Perovskite-Based Pure Red Light-Emitting Diodes through Interface Engineering with CsPbCl3 Quantum Dots

To optimize charge carrier injection and reduce interfacial losses in perovskite light-emitting diodes (PeLEDs), we introduced a thin interfacial layer of CsPbCl3 quantum dots (QDs) between the red quasi-two-dimensional (PEA5NMA5)0.2CsPb2I7 emitting layer and the electron transport layer (ETL). This interlayer markedly enhances the device performance, which we attribute to multiple synergistic effects. First, the structural compatibility between CsPbCl3 QDs and emitters enables a seamless interface, improving film morphology and interfacial contact. Second, the CsPbCl3 QDs serve as a passivation layer that mitigates surface trap states and suppresses iodine ions diffusion and halide vacancy-induced nonradiative recombination in emitter. Additionally, the wide bandgap and suitable conduction band position of CsPbCl3 QDs create a favorable energy-level cascade, facilitating efficient electron injection from ETL into the emitting layer while simultaneously blocking holes. These combined effects result in enhanced electroluminescence efficiency and improved operational stability. As a result, pure red PeLEDs achieve an impressive external quantum efficiency of 23.7% as well as a 15-fold increase in operational life.