Surface-modified ultra-thin indium tin oxide electrodes for efficient perovskite light-emitting diodes

Perovskite light-emitting diodes (PeLEDs) are promising lighting sources owing to their unique optical and electrical properties, such as high color purity and charge carrier mobility. Various material strategies have been reported to increase the radiative recombination rate and alleviate the non-radiative recombination rate of PeLEDs. However, PeLEDs are prone to low device efficiencies owing to the metal-induced exciton quenching caused by the diffusion of metal species from the indium tin oxide (ITO) electrodes into the emissive layer. Herein, we demonstrate that surface modification of ITO by means of electric-field-induced Ni doping treatment prevents the diffusion of metal species and helps tune the work function. The effects of Ni doping on ITO (Ni-ITO) are clarified by conducting X-ray photoelectron spectroscopy, time of flight-secondary ion mass spectrometry, and energy level investigations. A PeLED fabricated using Ni-ITO as the anode exhibited a maximum current efficiency of 91.11 cdA^-1 and external quantum efficiency of 20.48%, which are 13.5% and 13.9% higher than those of the PeLED fabricated using a commercially available ITO film (with a thickness of 180 nm), respectively. The results of this study can be used as guidelines to increase the quantum efficiencies of ITO-based organic/inorganic emitter devices and PeLEDs.