Blue Perovskite Light-Emitting Diodes Using Multifunctional Small Molecule Dopants.

Area of Science:

• Materials Science
• Optoelectronics
• Chemistry

Background:

• High-efficiency blue perovskite light-emitting diodes (LEDs) face challenges from unbalanced charge carrier injection and non-radiative recombination.
• Defect control and balanced charge injection are crucial for improving the performance of perovskite LEDs.

Purpose of the Study:

• To develop a strategy for enhancing blue perovskite LEDs by addressing charge injection imbalance and defect-related losses.
• To investigate the effect of a specifically designed small molecule dopant on perovskite film properties and device performance.

Main Methods:

• Synthesized and incorporated a p-type small molecule, (2-(3,6-dibromo-9H-carbazol-9-yl)ethyl)phosphonic acid, into blue perovskite films.
• Utilized the unique extrusion behavior of the small molecule during film deposition to form surface layers.
• Fabricated and characterized blue perovskite LEDs incorporating the doped perovskite films.

Main Results:

• The small molecule dopant, extruded to the surfaces, facilitated balanced carrier injection by improving hole injection and retarding electron injection.
• Covalent bond formation by the molecule's functional moiety effectively passivated bulk and surface defects in the perovskite films.
• Achieved high external quantum efficiencies (EQEs) for blue perovskite LEDs: up to 24.03% (485 nm), 16.61% (476 nm), and 8.55% (467 nm).
• Demonstrated encouraging operational stability for the fabricated devices.

Conclusions:

• The developed small molecule doping strategy effectively balances charge injection and passivates defects in blue perovskite films.
• This approach significantly enhances the efficiency and stability of blue perovskite light-emitting diodes (LEDs).
• The findings offer a promising pathway for the advancement of high-performance blue perovskite optoelectronic devices.