Plasticizer Design Principle of "Like Dissolves Like": Semiconductor Fluid Plasticized Stretchable Fully π-Conjugated...

Area of Science:

• Materials Science
• Polymer Chemistry
• Optoelectronics

Background:

• Physical blending of fully π-conjugated polymers (FπCPs) is used for stretchable films in flexible optoelectronics.
• Blending often leads to phase separation, poor morphology, and reduced performance in deep-blue flexible polymer light-emitting diodes (FPLEDs).

Purpose of the Study:

• To develop intrinsically stretchable FπCP films using external plasticization for high-performance deep-blue FPLEDs.
• To establish a "Like Dissolves Like" design principle for creating effective semiconductor fluid plasticizers (SFPs).

Main Methods:

• Proposed three requirements for SFPs: similar conjugated skeleton, molecular polarity, and electronic structures.
• Prepared nonpolar M1 and polar M2 plasticizers for poly(9,9-dioctylfluorene) (PFO) based on the principle.
• Fabricated and characterized large-area plasticized PFO films and deep-blue FPLEDs.

Main Results:

• Plasticized PFO films showed efficient, narrowband, stable ultra-deep-blue electroluminescence (FWHM < 40 nm, CIE: 0.12, 0.04).
• Films exhibited uniform morphology and excellent intrinsic stretchability (fracture strain >20%, crack-onset strain >120%).
• Deep-blue FPLEDs achieved high brightness (≈3000 cd cm⁻²) and demonstrated outstanding stretch-deformation cycling stability.

Conclusions:

• The "Like Dissolves Like" principle effectively designs matched SFPs for stretchable FπCP films.
• This approach overcomes phase separation issues, enabling high-performance stretchable deep-blue FPLEDs.
• The developed SFPs are crucial for advancing flexible electronics and optoelectronic applications.