High Electron Affinity Molecular Dopant CN6-CP for Efficient Organic Light-Emitting Diodes

Area of Science:

• Organic electronics
• Materials science
• Optoelectronics

Background:

• p-Type molecular doping of organic materials with high ionization energies (IEs) above 5.50 eV is a significant challenge.
• This limitation hinders the development of high-performance organic light-emitting diodes (OLEDs).

Purpose of the Study:

• To investigate hexacyano-trimethylene-cyclopropane (CN6-CP) as a novel p-type dopant for organic materials.
• To evaluate the performance of CN6-CP in OLED devices, particularly with host materials possessing high IEs.

Main Methods:

• Investigated CN6-CP as a dopant in TAPC (IE = 5.50 eV) and TCTA (IE = 5.85 eV).
• Fabricated and characterized green phosphorescent OLEDs using CN6-CP-doped TAPC and TCTA as hole injection/transport layers.
• Measured conductivity, absorption, driving voltage, external quantum efficiency, and luminous efficacy.

Main Results:

• CN6-CP achieved a conductivity of 1.86 × 10^-4 S/cm in TCTA at a 0.25 molar ratio.
• OLEDs with CN6-CP-doped TAPC showed a low driving voltage (2.92 V at 1000 cd/m²) and high efficiency (18% EQE, 78 lm/W).
• CN6-CP-doped TCTA further reduced driving voltage (2.78 V at 1000 cd/m²) and showed potential for doping CBP (IE = 6.05 eV).

Conclusions:

• CN6-CP is a highly effective p-type dopant for organic materials with high ionization energies.
• CN6-CP enables efficient OLEDs with low driving voltages and excellent performance metrics.
• CN6-CP shows great potential for future applications in organic optoelectronics.