A Fluorescent Conjugated Polar Polymer for Probing Charge Injection in Multilayer Organic Light-Emitting Transistors

Area of Science:

• Materials Science
• Organic Electronics
• Optoelectronics

Background:

• Ambipolar organic light-emitting transistors (OLETs) offer combined switching and light emission but suffer from low external quantum efficiency (EQE) and brightness.
• Interface engineering between electron-transporting organic semiconductors (e-OS) and emission layers (EML) is critical for optimizing charge recombination and device performance.

Purpose of the Study:

• To introduce a novel conjugated polar polymer (CPP) into multi-stacked OLETs to enhance electron injection from e-OS to EML.
• To investigate the impact of CPPs on electroluminescence processes, including exciton formation and quenching.
• To explore the role of polar groups in CPPs on charge trapping and electrostatic field modulation.

Main Methods:

• Fabrication of multi-stacked OLET devices incorporating a newly synthesized conjugated polar polymer (CPP).
• Characterization of charge injection, electroluminescence, and optoelectronic properties.
• Analysis of charge-trapping phenomena and electrostatic field distribution influenced by the polar groups in CPPs.

Main Results:

• The introduction of CPPs significantly improved electron injection from the e-OS to the EML.
• Highly polar groups in the CPP induced polarization-related charge-trapping, altering the electrostatic field distribution.
• Unexpected optoelectronic features and enhanced light-emission properties were observed due to the CPP's influence.

Conclusions:

• Multifunctional CPPs are effective in improving electron injection and light-emission properties in OLETs.
• The study highlights the potential of CPPs for probing photophysical processes at functional interfaces in stacked devices.
• This work paves the way for accelerating advancements in OLET technology through rational material design.