Hard-Soft-Acid-Base Management Enabled Bright and Stable Pure-Blue Perovskite Quantum Dot LEDs.

Area of Science:

• Materials Science
• Quantum Dot Technology
• Optoelectronics

Background:

• Perovskite quantum dot (QD) LEDs show high efficiency in green and red regions.
• Pure-blue perovskite QD LEDs struggle with low efficiency at high luminance due to weak ligand-surface binding.

Purpose of the Study:

• To address the low efficiency of pure-blue perovskite QD LEDs at high luminance.
• To identify strategies for enhancing ligand-surface binding in perovskite QDs.

Main Methods:

• Utilized first-principles calculations to assess hard-soft-acid-base interaction strengths.
• Investigated alkali metal ions for improved ligand binding to perovskite QDs.
• Employed rubidium ions to strengthen the binding with bromine dangling bonds.

Main Results:

• Rubidium ions demonstrated optimal softness for binding with bromine dangling bonds in QDs.
• Achieved a photoluminescence quantum yield of 81% for the QD film.
• Developed low-defect QD films enabling efficient carrier recombination.
• Demonstrated a record peak external quantum efficiency (EQE) of 15.7% at 3916 cd m^-2 for pure-blue perovskite QD LEDs.
• Maintained high EQE (14.9%) at a higher luminance of 5371 cd m^-2.
• Achieved a 35-fold improvement in EQE × luminance compared to previous blue perovskite LEDs.

Conclusions:

• Rubidium ion incorporation effectively strengthens ligand binding in perovskite QDs.
• The developed strategy significantly enhances the performance of pure-blue perovskite QD LEDs.
• This work sets a new benchmark for blue perovskite QD LED efficiency and luminance.