Spacer engineering of quasi-2D perovskites for high-efficiency light-emitting diodes

Abstract

Perovskite light-emitting diodes (PeLEDs have developed rapidly in the past decade, and had attention as next-generation luminescent devices. The high luminescence efficiency of perovskite can be attributed to the spin-orbital coupling of heavy elements and the absence of inversion symmetry in the lattice. In this study, we synthesized perovskite using the asymmetric spacer, 2-(2-aminoethyl) isothiourea dihydrobromide (AIT) to investigate the possibility which improve by the asymmetricity. I adjusted cation composition and solvents in order to fabricate high luminescence film. (PLQY > 40%) In addition, there is correlation between slab distribution of quasi-2D perovskite and nanocrystal pinning (NCP) time by the saturation model. Furthermore, I indirectly assessed asymmetry's efficiency enhancement by examining spacer functional groups. The AIT, with asymmetry, has the maximum external quantum efficiency (EQE) of 3% and luminance of 1000 nit. Additionally, an interface defect passivation layer between the hole transport layer and the emissive layer further improves device efficiency, resulting in an EQE of 6% and a luminance of approximately 5000 nit.