Flat, Luminescent, and Defect-Less Perovskite Films on PVK for Light-Emitting Diodes with Enhanced Efficiency and Stability

Metal-halide perovskites have broad application prospects in being emitters for light-emitting diodes (LEDs) on account of their remarkable photoelectric performance. Nevertheless, exciton quenching induced by the poor quality of perovskite films and mismatched energy levels between the perovskite layer and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) restricts device performance. This study presents poly(9-vinylcarbazole) (PVK) films processed by a polar solvent as the hole transport layer to construct efficient perovskite LEDs (PeLEDs). The perovskite film on PVK exhibited a smoother surface, smaller grain size, and fewer defects, which improved its luminescence properties in comparison to that formed on PEDOT:PSS. Moreover, the lower energy barrier between PVK and the emission layer improved the hole injection. Based on the high luminescence and electrical transport characteristics, the device exhibited improved performance with a peak external quantum efficiency reaching 10.59%. Furthermore, the LEDs showed excellent environmental and operational stability because the hydrophobic PVK shielded the perovskite from atmospheric moisture and restricted interfacial exciton quenching. These results demonstrate that the PVK is an effective hole injection and transport material that can be applied to photodetectors, solar cells, memristors, and similar devices.