Jingbi You1
Chinese Academy of Sciences1
Jingbi You1
Chinese Academy of Sciences1
Perovskite light-emitting diodes (PeLEDs) have showed significant progresses in recent years, the external quantum efficiency (EQE) of electroluminescence in green and red regions have been beyond 20%, and the efficiency in blue is lagged out. Here, I will represent our two recent progresses in efficient blue PeLEDs <i>via</i> energy-band engineering. 1) We introduced a large cation CH<sub>3</sub>CH<sub>2</sub>NH<sub>2</sub><sup>+</sup> (EA) into the Cs<sup>+</sup> site in PEA<sub>2</sub>(CsPbBr<sub>3</sub>)<sub>2</sub>PbBr<sub>4</sub> perovskite with green emission to decrease the Pb-Br orbit coupling and increase the bandgap for blue emission. And as high as 12.1% EQE of sky-blue electroluminescence located at 488 nm has been demonstrated. 2）By doping the hole injection layer with alkali metal salt, a more matching energy level arrangement is obtained, and the hole injection efficiency is improved. At the same time, the defect states in the perovskite films are passivated and/or suppressed, and the electroluminescence efficiency of blue PeLEDs is up to 16.07%.