Eu2+ ions as an antioxidant additive for Sn-based perovskite light-emitting diodes

Abstract

Sn-Based perovskite materials are environmentally benign and have low toxicity with excellent light emitting ability, and are ideal choices for light-emitting diode (LED) active layers. However, the tendency of Sn²⁺ to be oxidized to Sn⁴⁺ leads to increased crystalline defects and chemical instability, which hamper the external quantum efficiency of LEDs. Herein, we introduce Eu²⁺ ions as the electron donor to provide a reducing environment to suppress the oxidation of Sn²⁺, and as a stabilizer to adjust the growth of the perovskite film simultaneously. Techniques such as X-ray photoelectron spectroscopy, transient absorption, and scanning electron microscopy have confirmed that Eu²⁺ ion doping can increase the film quality and decrease the Sn⁴⁺ defect density. Benefiting from these merits, the LED based on (PEA)₂SnI₄ film emits pure-red radiation with a maximum brightness of 221 cd m⁻² and a high EQE up to 1.48%.