Ultrabright Blue Lead-Halide Perovskite Light-Emitting Diodes Based on Phosphonic Acid Functionalized Hole Injection...

Area of Science:

• Materials Science
• Optoelectronics
• Chemistry

Background:

• Lead-halide perovskite light-emitting diodes (PeLEDs) offer high efficiency and radiance, particularly in green and near-infrared spectrums.
• Pure blue PeLEDs (<480 nm) face significant challenges, primarily severe luminance-efficiency roll-off, hindering their practical application.
• Phosphonic acid functional carbazoles (PACs) are promising hole injection layers but suffer from limitations in small-molecule forms.

Purpose of the Study:

• To achieve ultrabright pure blue PeLEDs with minimized efficiency roll-off at high brightness.
• To address the limitations of small-molecule PACs in hole injection layers for blue PeLEDs.
• To resolve the interfacial property puzzles of PACs and guide future material design.

Main Methods:

• Investigated the limitations of small-molecule PACs, including leakage currents due to uneven surface coverage and nanoisland structures.
• Developed and utilized polymeric PACs as hole injection layers in pure blue PeLEDs.
• Characterized device performance, including peak luminance, efficiency roll-off, and pulsed driven brightness.

Main Results:

• Demonstrated ultrabright pure blue PeLEDs with a peak luminance of ~29,800 cd m⁻² (478 nm, CIEy < 0.15).
• Achieved high brightness up to ~140,000 cd m⁻² under pulsed driving, with significantly minimized efficiency roll-off.
• Identified that polymeric PACs overcome the issues associated with small-molecule PACs, such as leakage currents.

Conclusions:

• Polymeric PACs are crucial for developing high-performance pure blue PeLEDs, overcoming previous limitations.
• The study provides essential guidance for designing efficient blue PeLEDs and understanding PAC interfacial properties.
• This work advances the application of lead-halide perovskites in high-radiance blue light-emitting technologies.