Approaching-unity PLQY and high stretchability in polymer emitters via molecular spacers

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Chemistry

Background:

• Stretchable organic light-emitting diodes (OLEDs) are crucial for wearable technology but face challenges balancing mechanical stretchability with high light emission efficiency.
• Existing methods struggle to overcome the inherent trade-off between flexibility and performance in OLED materials.

Purpose of the Study:

• To develop a broadly applicable strategy for enhancing both stretchability and light-emitting performance in thermally activated delayed fluorescence (TADF) polymers.
• To investigate the role of optoelectronically inert small-molecule plasticizers in improving the properties of TADF polymers for OLED applications.

Main Methods:

• Incorporation of small-molecule plasticizers, such as dioctyl phthalate (DOP), into TADF polymers.
• Analysis of plasticizers acting as molecular spacers to expand free volume and suppress triplet exciton quenching.
• Evaluation of stress-dissipative chain mobility facilitated by plasticizer incorporation.

Main Results:

• Achieved photoluminescence quantum yield (PLQY) approaching unity.
• Demonstrated mechanical stretchability exceeding 110% strain.
• Improved electroluminescent efficiency, with external quantum efficiency (EQE) reaching 12.6% in rigid devices and 3.05% in stretchable OLEDs.

Conclusions:

• Plasticizer engineering is a simple, scalable design principle for creating intrinsically stretchable optoelectronic materials.
• The strategy is effective across various TADF polymers, offering a pathway to advanced wearable displays and biointerfaces.