Perovskite light-emitting diodes with external quantum efficiency exceeding 20 per cent.

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Metal halide perovskites are promising solution-processable semiconductors for optoelectronics.
• Current perovskite LEDs lag behind organic and quantum dot LEDs in external quantum efficiency (EQE).
• Existing green and red perovskite LEDs show EQEs of approximately 14% and 12%, respectively.

Purpose of the Study:

• To surpass the 20% external quantum efficiency (EQE) milestone for visible-light-emitting perovskite LEDs.
• To develop a strategy for managing compositional distribution to enhance luminescence and charge injection.
• To advance the practical application of perovskite LEDs in displays and lighting.

Main Methods:

• A novel quasi-core/shell structure was created by mixing CsPbBr3 perovskite with a MABr additive.
• Sequential crystallization, driven by differing solubilities, formed the CsPbBr3/MABr structure.
• The MABr shell passivates non-radiative defects and the capping layer ensures balanced charge injection.

Main Results:

• Achieved a record external quantum efficiency (EQE) of 20.3% for visible-light-emitting perovskite LEDs.
• Demonstrated simultaneous enhancement of photoluminescence quantum efficiency and charge injection.
• The MABr shell effectively passivated non-radiative defects in CsPbBr3 crystals.

Conclusions:

• The developed perovskite LED strategy significantly boosts performance, exceeding 20% EQE.
• This advancement addresses key limitations in perovskite LED technology.
• The findings represent a major step towards commercializing perovskite LEDs for lighting and display applications.