Interfacial Chemistry Limits the Stability of Deep Blue Perovskite LEDs Revealed by Operando Characterization

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Commercialization of lead halide perovskites in light-emitting diodes (LEDs) is hindered by insufficient operational device lifetime.
• Understanding degradation mechanisms under electrical bias is critical for enhancing LED stability.

Purpose of the Study:

• To investigate the structural, chemical, and electronic changes in deep blue mixed bromide/chloride lead halide perovskite LEDs under electrical bias.
• To identify the primary degradation pathways affecting the optoelectronic performance and operational stability of these devices.

Main Methods:

• Utilized operando synchrotron-based grazing-incidence wide-angle X-ray scattering (GIWAXS) to monitor structural properties.
• Employed hard X-ray photoelectron spectroscopy (HAXPES) to analyze chemical and electronic changes at interfaces.
• Measured optoelectronic performance under electrical bias in full-stack perovskite LED devices.

Main Results:

• A significant drop in optoelectronic performance was observed under electrical bias.
• Operando GIWAXS showed minimal changes in the perovskite structure.
• HAXPES revealed substantial chemical alterations at the electron-injecting interface, including the formation of metallic lead and a novel chlorine species.

Conclusions:

• Degradation in lead halide perovskite LEDs under bias is primarily driven by interfacial chemical changes, not bulk structural modifications.
• The formation of metallic lead and new chlorine species at the electron-injecting interface significantly impacts device performance.
• Targeting and stabilizing the top electron-injecting interface is essential for achieving significant improvements in the operational stability of perovskite LEDs.