Record efficiency of 1000 nm electroluminescence from a solution-processable host-free OLED

Area of Science:

• Coordination Chemistry
• Materials Science
• Organic Electronics

Background:

• Ytterbium complexes are explored for optoelectronic applications.
• Charge transport properties and photoluminescence quantum yield (PLQY) are key performance indicators for OLED materials.

Purpose of the Study:

• To synthesize and characterize novel ytterbium complexes with 2-tosylaminobenzylidene-aryloylhydrazones.
• To investigate the impact of structural modifications on charge mobility, PLQY, and electroluminescence efficiency in OLEDs.

Main Methods:

• Synthesis of K(Solv)[Yb(L)2] complexes.
• Measurement of hole and electron mobility.
• Determination of photoluminescence quantum yield (PLQY).
• Fabrication and testing of OLED devices.

Main Results:

• The synthesized ytterbium complexes showed high solubility and hole mobility (ca. 2.6 × 10^-6 cm^2 V^-1 s^-1).
• Substitution from benzoyl to naphthoyl significantly increased electron mobility (6.9 × 10^-7 to 1.7 × 10^-6 cm^2 V^-1 s^-1) but decreased PLQY (1.2% to 0.6%).
• Optimized OLEDs achieved record Ytterbium electroluminescence efficiencies up to 441 μW W^-1, highlighting the dominance of charge mobility.

Conclusions:

• Charge mobility is more critical than PLQY for achieving high electroluminescence efficiency in these Ytterbium-based OLEDs.
• The developed ytterbium complexes represent a significant advancement in Ytterbium electroluminescence technology.