Polymer Hosts Containing Carbazole-Dibenzothiophene-Based Pendants for Application in High-Performance...

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Chemistry

Background:

• The performance of organic light-emitting diodes (OLEDs) relies heavily on the host material's film-forming ability for solution processing.
• Carbazole and dibenzothiophene moieties are common building blocks in host materials for efficient light emission.

Purpose of the Study:

• To synthesize and evaluate novel side-chain polymer hosts for solution-processed OLEDs.
• To investigate the impact of polymer structure on thermal stability and film morphology.
• To assess the performance of devices utilizing these polymer hosts in thermally activated delayed fluorescence (TADF) applications.

Main Methods:

• Radical polymerization of styrene-based monomers to synthesize PCz-DBT and P2Cz-DBT polymer hosts.
• Characterization of photophysical properties and molecular energy levels.
• Fabrication and testing of OLED devices using the synthesized polymer hosts, including blend films with emitters.
• Performance evaluation of devices based on P2Cz-DBT for bluish-green multiple-resonance (MR) TADF OLEDs.

Main Results:

• The synthesized polymer hosts (PCz-DBT and P2Cz-DBT) exhibit similar photophysical and energy level characteristics to small-molecule counterparts (Cz-DBT and 2Cz-DBT).
• The polymer hosts demonstrate superior thermal stability and enhanced film-forming properties compared to small-molecule hosts.
• Solution-processed TADF OLEDs utilizing P2Cz-DBT achieved a maximum external quantum efficiency of 17.4% without a hole transport layer.

Conclusions:

• Side-chain polymer hosts offer advantages in thermal stability and film formation for solution-processed OLEDs.
• The P2Cz-DBT polymer host enables high-performance bluish-green TADF OLEDs fabricated via solution processing.
• This polymer host design strategy is promising for advancing solution-processed OLED technology.