Stable Yellow Light-Emitting Diodes Based on Quasi-Two-Dimensional Perovskites

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Chemistry

Background:

• Perovskite light-emitting diodes (PeLEDs) offer tunable wavelengths, narrow emission, and high color purity for displays and lighting.
• While red and green PeLEDs achieve high external quantum efficiency (EQE) (>23%), yellow PeLEDs remain underdeveloped due to phase separation issues in mixed-halide and quasi-two-dimensional (quasi-2D) perovskites.

Purpose of the Study:

• To develop stable and efficient yellow PeLEDs.
• To address the challenges of phase separation and multi-phase coexistence in quasi-2D perovskites for yellow emission.

Main Methods:

• Fabrication of quasi-2D perovskites using butyl ammonium (BA) ligand for narrower phase distribution.
• Incorporation of rubidium cations (Rb+) into (BA)2CsPb2I7 perovskite to tune emission wavelength.
• Characterization using transient absorption spectroscopy to confirm phase distribution.

Main Results:

• Butyl ammonium (BA) demonstrated a narrower phase distribution compared to phenylethyl ammonium (PEA) in quasi-2D perovskites, leading to a blue-shifted emission.
• Incorporation of Rb+ successfully blue-shifted the emission peak into the yellow range.
• The fabricated yellow PeLEDs achieved an EQE of 3.5% with a stable emission peak at 595 nm.

Conclusions:

• Manipulating phase distribution and incorporating Rb+ are effective strategies for creating stable yellow PeLEDs.
• This work provides a viable method for producing highly efficient and stable yellow PeLEDs, advancing display and lighting technologies.