Ion dissociation in crown ether based wide band gap LECs

The Influence of the Phase Morphology on the Optoelectronic Properties of Light‐Emitting Electrochemical Cells

“…From infrared spectroscopic studies on this blend layer it is known that the main part of the cations is coordinated by the crown ethers. [26] Predominantly free ions (and to a certain extent ion pairs) were observed within these studies, showing some solubilization of the salt by the crown ether moiety and thereby a correlation of coordinated crown ethers and ionic species. We therefore attribute the harder and the softer phases mainly to be due to crown ether salt complexes that phase separate from the mLPPP crown ether blend after complexation, a behavior also known for PMMA/PEO blends, which readily phase separate upon the addition of a salt.…”

“…[21] The methyl-substituted LPPP (mLPPP) derivative has a methyl substituent attached to the methine bridge in order to increase interchain distances, and it has successfully been applied in OLEDs, [22] LECs, [23,24] and solid-state organic lasers. [25] The optoelectronic properties of mLPPP-based LECs using either an HMWPEO [23,24] or a crown ether (dicyclohexano-18-crown-6 (DCH18C6)) [26] -based solid-state electrolyte are already published. 18C6 in combination with a Li salt was chosen in order to maintain some ionic conductivity because of the mismatch of the Li radius and the crown ether diameter.…”

“…[23,24] This behavior was observed to be independent of the kind of anions investigated, LiCF 3 SO 3 and LiClO 4 . [27] This asymmetry is char- [27]) or DCH18C6 (solid line, see [26]) as a solid-state electrolyte. The inset shows the chemical structure of mLPPP.…”

“…[26] The absolute value of the luminance in forward and reverse direction varies slightly from sample to sample, but it generally exceeds 500 cd m ±2 (measured at ±5 V, the minus sign refers to the reverse directionÐITO wired as a cathode for a direct comparison with the HMWPEO-based LECs). Thus, the luminance is more than ten times higher than for the HMWPEO-based devices.…”

“…In the earlier studies on the optoelectronic properties, the LECs with the best performances were obtained for a blend composition of mLPPP/HMWPEO/LiTf = 20:10:3±4 [23,24,27] and mLPPP/DCH18C6/LiTf = 20:20:4 by weight, [26] spin-cast from a cyclohexanone co-solution. Cyclohexanone is the favored choice, since all the components discussed below (mLPPP, DCH18C6, HMWPEO, and LiTf) can be separately dissolved in this solvent.…”