High brightness blue light-emitting diodes based on CsPb(Cl/Br)3 perovskite QDs with phenethylammonium chloride passivation

Abstract

All inorganic perovskite quantum dots (QDs) (CsPbX₃, X = Cl, Br, I) have been applied on light-emitting devices (LEDs) in recent years due to their excellent optical and optoelectronic properties. However, blue-light emitting perovskite QD LEDs (PQD-LEDs) exhibit poor performances compared with their green- and red-light emitting counterparts. Herein, we fabricated high performing blue-light emitting PQD-LEDs based on phenethylammonium chloride (PEACl) modified CsPb(Cl/Br)₃ QDs. Firstly, the PEA-CsPbCl₃ QDs were synthesized by introducing certain amounts of PEACl in the conventional hot-injection synthesis process. The merit of our synthesis lies in the fact that not only the Cl vacancies of CsPbCl₃ QDs are efficiently modified by introducing the PEACl precursor, but also the partial long-chain organic ligands (OLA) capping on the surface of CsPbCl₃ QDs are simultaneously replaced by shorter PEACl chains. Consequently, the PEA-CsPbCl₃ QDs emitting at 410 nm with a PLQY of 62.3% were achieved. Furthermore, to meet the requirement of display applications, we exchanged Cl⁻ with Br⁻ ions at room temperature to precisely control the blue emission in the 460–470 nm spectral region and with a maximum PLQY of 80.2% at 470 nm. Finally, the PQD-LEDs based on PEA-CsPb(Cl/Br)₃ perovskite QDs emitting at 462, 465, 468 and 470 nm were fabricated. The PQD-LEDs exhibit a maximal EQE of 2.15% and luminance of 620 cd m⁻², which provides the highest value of luminance for the PQD-LEDs in the blue spectral range that satisfies the requirement of practical display applications.