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

New ytterbium complexes K(Solv)(x)[Yb(L-n)(2)] (Solv = ethanol and/or water) with 2-tosylaminobenzylidene-aryloylhydrazones (H2L1, aryloyl = benzoyl; H2L2, aryloyl = 2-naphthoyl) demonstrated high solubility and hole mobility (ca. 2.6 x 10(-6) cm(2) V-1 s(-1)), while their electron mobility and PLQY were different. The substitution of a benzoyl substituent with naphthoyl resulted in a significant increase of the electron mobility (6.9 x 10(-7)vs. 1.7 x 10(-6) cm(2) V-1 s(-1)) and a decrease of the quantum yield (1.2% vs. 0.6%). As a result, the optimized OLEDs based on the K[Yb(L-n)(2)] layer demonstrated efficiencies up to 385 mu W W-1 and 441 mu W W-1, indicating the superior importance of charge mobility over the quantum yield. These are the highest efficiencies of the Yb electroluminescence.

Automated summary

New ytterbium complexes exhibited high solubility and hole mobility, while their electron mobility and PLQY differed. Substituting a benzoyl group with a naphthoyl group increased electron mobility but decreased the quantum yield. Charge mobility was found to be more important for device efficiency than quantum yield.