Intragrain 3D perovskite heterostructure for high-performance pure-red perovskite LEDs

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Physics

Background:

• Metal-halide perovskites are key materials for next-generation light-emitting diodes (LEDs).
• Achieving high brightness and efficiency in pure-red perovskite LEDs (PeLEDs) remains a challenge.
• Three-dimensional (3D) CsPbI3-xBrx emitters offer potential for efficient and ultrabright PeLEDs but suffer from efficiency roll-off.

Purpose of the Study:

• To investigate the cause of efficiency roll-off in 3D CsPbI3-xBrx pure-red PeLEDs.
• To develop a strategy to overcome efficiency roll-off and enhance device performance.
• To create bright and efficient pure-red PeLEDs with improved operational stability.

Main Methods:

• Electrically excited transient absorption spectroscopy was used to identify the mechanism of efficiency roll-off.
• A CsPbI3-xBrx intragrain heterostructure was engineered with narrow bandgap emitters and wide bandgap barriers.
• Strongly bonding molecules were introduced into the [PbX6]4- framework to expand the lattice and form the wide bandgap barrier.

Main Results:

• Electrically excited transient absorption spectroscopy revealed that hole leakage induces efficiency roll-off.
• The developed intragrain heterostructure effectively confines injected carriers.
• The engineered PeLEDs achieved a high brightness of 24,600 cd/m², a maximum external quantum efficiency (EQE) of 24.2%, and maintained 10.5% EQE at 22,670 cd/m².

Conclusions:

• Hole leakage is the primary cause of efficiency roll-off in 3D CsPbI3-xBrx pure-red PeLEDs.
• The intragrain heterostructure design successfully mitigates carrier leakage and improves device performance.
• This work presents a viable pathway towards highly bright, efficient, and stable pure-red PeLEDs.