Improved Electroluminescence Performance of Perovskite Light-Emitting Diodes by a New Hole Transporting Polymer Based on the Benzocarbazole Moiety.

A new hole-transporting material, poly-2-(9H-carbazol-9-yl)-5-(4-vinylphenyl)-5H-benzo[b]carbazole (PBCZCZ), was developed for perovskite light-emitting diodes (PeLEDs). This polymer, which is based on the benzocarbazole moiety, has good solubility in common solvents and enabled the fabrication of highly efficient multilayer perovskite devices. It has excellent film morphology and a high hole mobility of 3.67 × 10-5 cm2 V-1 s-1, which made it possible to vary the device configuration. Green and sky-blue perovskite PeLEDs using PBCZCZ as the hole-transporting layer had current efficiencies and external quantum efficiencies (EQEs) of 43.90 cd A-1 and 8.67% for the green device and 9.07 cd A-1 and 4.04% for the sky-blue device, respectively. The EQE of the green PeLEDs was about 2.5 times higher and that of the sky-blue PeLEDs was about 3 times higher than the device made with the commercial HTL of poly(9-vinylcarbazole) (PVK). The operational device lifetimes of the green and sky-blue PeLEDs made with PBCZCZ were about 4.1 and 4.8 times higher than the PVK-containing device, respectively.