Significant electroluminescence efficiency and stability enhancements in perovskite light-emitting diodes with double additives

Abstract

Perovskite light-emitting diodes (PeLEDs) as the next-generation display have been attracting wide attention due to high color purity, high photoluminescence quantum-yields (PLQYs), and easily tunable bandgap. Perovskite film quality has been being a fatal factor influencing electroluminescence (EL) performance of PeLEDs. The big pinholes and high roughness in the pristine CsPbBr3 perovskite film cause severely leakage current. In addition, the low PLQY indicates that the perovskite film retains poor radiative recombination. These may lead to a limited EL performance for PeLEDs. Therefore, in this work, to obtain an perovskite film with full coverage surface and desirable optical property, the long ligand 2-phenylethanamine bromide (PEABr) was introduced into CsPbBr3 perovskite solution firstly. After the introduction of PEABr, the photoluminescence (PL) intensity and perovskite morphology quality have been improved. Meanwhile, the exiton quantum confinement is enhanced by the layerd structure in the PEA2Csn-1PbnBr3n+1 perovskite film. Secondly, an organic molecule, named benzyltriphenylphosphonium chloride (BTPPC), was further introduced into the perovskite precursor solution to enhance crystallization process to obtain a better perovskite film with less pinholes and smaller grains. Finally, the PeLEDs with two additives achieved the best external quantum efficiency (EQE) of 11.9%, which is 45.7-fold to that of the pristine device. And the stability of the PeLEDs can be improved from 240 s to 2079 s under an initial luminance of 1000. cd/m2.