Charge generation layers for solution processed tandem organic light emitting diodes with regular device...

Area of Science:

• Materials Science
• Organic Electronics
• Device Physics

Background:

• Tandem organic light-emitting diodes (OLEDs) offer enhanced efficiency and brightness by stacking multiple emissive layers.
• Solution-based fabrication methods are crucial for cost-effective and large-scale OLED production.

Purpose of the Study:

• To fabricate and characterize solution-processed tandem OLEDs utilizing fluorescent polymers.
• To investigate the performance of different charge carrier generation layers for efficient charge injection.

Main Methods:

• Fabrication of tandem OLED devices from solution.
• Characterization of device structure using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Scanning Transmission Electron Microscopy with Energy-Dispersive X-ray spectroscopy (STEM-EDX).
• Performance evaluation of current efficiency under specific current densities.

Main Results:

• Successfully fabricated solution-processed tandem OLEDs with distinct functional layers confirmed by ToF-SIMS and STEM-EDX.
• Employed a charge carrier generation layer with zinc oxide and polyethylenimine for electron injection, and MoO3, WO3, or VOx for hole injection.
• Achieved combined current efficiencies of up to 25 cd/A for the tandem OLEDs at a given current density.

Conclusions:

• The fabricated tandem OLEDs demonstrate efficient charge carrier generation and injection.
• Solution-based fabrication is a viable route for producing high-performance tandem OLEDs.
• The results indicate a properly functioning tandem OLED architecture with additive efficiencies from sub-OLEDs.