Vertically Concentrated Quantum Wells Enabling Highly Efficient Deep-Blue Perovskite Light-Emitting Diodes.

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Physics

Background:

• Deep-blue perovskite light-emitting diodes (PeLEDs) are sensitive to domain distribution, impacting performance.
• Traditional crystallization leads to unfavorable vertical quantum well (QW) gradients, hindering deep-blue emission.

Purpose of the Study:

• To develop a thermal gradient annealing treatment to control vertical QW polydispersity in quasi-2D perovskites.
• To improve the efficiency and stability of deep-blue PeLEDs.

Main Methods:

• Utilized thermal gradient annealing to create a controlled low-temperature zone during perovskite film formation.
• Incorporated NaBr to suppress undesirable n=1 domains.
• Fabricated and characterized quasi-2D PeLED devices.

Main Results:

• Achieved a vertically concentrated QW structure, inhibiting large-n domain formation.
• Demonstrated a deep-blue PeLED emitting at 458 nm with 5.82% external quantum efficiency (EQE).
• Successfully produced green and sky-blue PeLEDs with high EQEs of 21.83% and 17.51%, respectively, using the same strategy.

Conclusions:

• The thermal gradient annealing offers a universal strategy for optimizing quasi-2D perovskites.
• This method effectively addresses vertical QW polydispersity, enabling high-performance deep-blue emission.
• The findings support the practical application of PeLEDs across various colors.