Highly Efficient Spectrally Stable Red Perovskite Light-Emitting Diodes.

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Chemistry

Background:

• Perovskite light-emitting diodes (LEDs) offer narrow emissions and solution processability.
• Significant advancements exist for green perovskite LEDs, but red and blue perovskite LEDs lag behind.
• Developing efficient and stable red perovskite LEDs is crucial for display and lighting applications.

Purpose of the Study:

• To develop highly efficient and spectrally stable red perovskite LEDs.
• To explore the use of quasi-2D perovskite/poly(ethylene oxide) (PEO) composite thin films for red light emission.
• To tune the emission color of perovskite thin films from red to deep red.

Main Methods:

• Fabrication of quasi-2D perovskite thin films by controlling molar ratios of organic (benzylammonium iodide) and inorganic salts (cesium iodide, lead iodide).
• Formation of perovskite/polymer composite thin films using poly(ethylene oxide) (PEO).
• Characterization of photoluminescence quantum efficiencies, film smoothness, and device performance (brightness, external quantum efficiencies (EQEs)).

Main Results:

• Tunable luminescent quasi-2D perovskite thin films with emission colors ranging from red to deep red were obtained.
• Perovskite/PEO composite films exhibited significantly higher photoluminescence quantum efficiencies and improved smoothness compared to neat perovskite films.
• Fabricated red perovskite LEDs demonstrated high brightness (e.g., 1392 cd m^-2) and external quantum efficiencies (EQEs) up to 6.23% at 680 nm.
• Exceptional electroluminescence spectral stability was observed during continuous device operation.

Conclusions:

• Quasi-2D perovskite/PEO composite thin films are a promising material for efficient and stable red perovskite LEDs.
• The developed red perovskite LEDs achieve high performance metrics and spectral stability, addressing a key challenge in the field.
• This work paves the way for the practical application of red perovskite LEDs in next-generation optoelectronic devices.