Solution-Processed Organic Light-Emitting Diodes Using a Photo-Crosslinkable Hole-Transporting Layer

Area of Science:

• Organic electronics
• Materials science
• Photochemistry

Background:

• Solution-processed organic light-emitting diodes (OLEDs) offer cost-effective manufacturing.
• Developing stable, solution-processable hole transporting layers (HTLs) is crucial for efficient OLEDs.
• Achieving solvent resistance in HTLs is key for multi-layer solution deposition.

Purpose of the Study:

• To develop a photo-crosslinkable HTL for solution-processed OLEDs.
• To investigate the effect of photocrosslinking on HTL properties and device performance.
• To enable subsequent solution deposition of emissive layers onto the HTL.

Main Methods:

• A blend of poly(bis-4-butylphenyl-N,N-bisphenyl)benzidine (poly-TPD) and bis(4-azido-2,3,5,6-tetrafluorobenzoate) (FPA) was used to form the HTL.
• Photo-crosslinking was induced to render the HTL insoluble in organic solvents.
• Red and green OLEDs were fabricated using solution processing with the crosslinked HTL.

Main Results:

• The photo-crosslinked poly-TPD:FPA (1 wt%) HTL exhibited enhanced solvent resistance compared to neat poly-TPD.
• Solution-processed OLEDs with the crosslinked HTL showed improved device performance.
• The crosslinking enabled the successful solution deposition of subsequent layers.

Conclusions:

• Photo-crosslinkable HTLs are effective for solution-processed OLEDs.
• The poly-TPD:FPA blend provides a robust and efficient HTL solution.
• This approach facilitates the development of high-performance, cost-effective OLEDs.