Regulating the Grain-Growth Surface for Efficient Near-Infrared Perovskite Light-Emitting Diodes

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Chemistry

Background:

• Metal halide perovskites are promising for next-generation light-emitting diodes (PeLEDs).
• Optimizing the buried interface between perovskite films and charge transport layers is crucial for high-performance PeLEDs.
• Defects at the buried interface impede perovskite growth and device performance.

Purpose of the Study:

• To develop a bottom-up strategy for modulating the perovskite film's buried interface.
• To enhance the quality of perovskite films and improve PeLED performance and stability.
• To investigate the role of formamidine acetate in optimizing perovskite growth and interface properties.

Main Methods:

• A bottom-up perovskite film modulation strategy using formamidine acetate (FAAc).
• In situ deprotonation between formamidinium (FA+) and ZnO to eliminate hydroxyl defects and tune energy levels.
• Fabrication and characterization of FAPbI3-based PeLEDs and mixed-halide PeLEDs.

Main Results:

• Vertical-oriented growth of high-quality perovskite films with minimized defects.
• Elimination of hydroxyl defects and modulated energy levels in the ZnO layer.
• Achieved a champion external quantum efficiency (EQE) of 23.84% for FAPbI3-PeLEDs.
• Enhanced operational stability and suppressed EQE roll-off.
• Demonstrated versatility by extending the strategy to other mixed-halide PeLED compositions.

Conclusions:

• Formamidine acetate is an effective agent for enhancing the buried interface in perovskite films.
• The developed strategy significantly improves PeLED performance, including EQE, stability, and roll-off.
• This approach offers a versatile and straightforward method for advancing perovskite optoelectronic devices.