Phosphonate-Substituted Chitosan With Complete Non-Conjugation Facilitates Efficient Hole Injection in Perovskite...

Area of Science:

• Materials Science
• Optoelectronics
• Chemistry

Background:

• Perovskite light-emitting diodes (PeLEDs) offer potential for advanced displays due to their efficiency and color purity.
• Charge injection imbalance at the indium tin oxide (ITO)/perovskite interface, caused by energy barriers, limits PeLED performance.
• Existing hole injection layers (HILs) like PEDOT:PSS face challenges in optimizing interfacial energy levels.

Purpose of the Study:

• To introduce non-conjugated phosphorylated chitosan (NCPC) as a novel HIL for PeLEDs.
• To investigate NCPC's ability to mitigate energy barriers and improve charge injection at the ITO/perovskite interface.
• To evaluate the impact of NCPC on the performance of red, green, and blue PeLEDs.

Main Methods:

• Synthesis and characterization of non-conjugated phosphorylated chitosan (NCPC).
• Fabrication of PeLED devices with NCPC as the HIL.
• Performance testing of PeLEDs, including external quantum efficiency (EQE) and turn-on voltage measurements.
• Analysis of interfacial energy level alignment and charge injection dynamics.

Main Results:

• NCPC effectively reduces energy barriers at the ITO/perovskite interface, enhancing interfacial interactions.
• Incorporation of NCPC leads to significant improvements in EQEmax for red (25.35%), green (25.45%), and blue (14.22%) PeLEDs.
• The red PeLED EQEmax at 670 nm achieved is among the top reported values.
• Reduced turn-on voltages and suppressed nonradiative recombination were observed with NCPC.

Conclusions:

• NCPC serves as a highly efficient HIL for PeLEDs, overcoming ITO/perovskite interfacial limitations.
• The use of environmentally friendly natural materials like NCPC offers a promising avenue for developing high-performance displays.
• This work provides a new strategy for designing advanced HILs to boost PeLED efficiency and stability.