TY - JOUR
T1 - An Ionic Liquid That Dissolves Semiconducting Polymers
T2 - A Promising Electrolyte for Bright, Efficient, and Stable Light-Emitting Electrochemical Cells
AU - Sakanoue, Tomo
AU - Yonekawa, Fumihiro
AU - Albrecht, Ken
AU - Yamamoto, Kimihisa
AU - Takenobu, Taishi
N1 - Publisher Copyright:
© 2017 American Chemical Society.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/7/25
Y1 - 2017/7/25
N2 - Light-emitting electrochemical cells (LECs) are composed of blends of semiconducting polymers and electrolytes, in which a unique cooperative action of ions and electrons induces a dynamic p-n junction for efficient emission. One of the crucial issues remaining in LECs is uniformity in blends of polymer and electrolyte; phase separation in between the two components results in poor performance or failure of operation. Here, we overcome this issue by developing an ionic liquid-based electrolyte of alkylphosphonium-phosphate that shows notable compatibility high enough to dissolve even light-emitting polymers. This exceptional compatibility enabled us to prepare uniform film blends with various blue to red emitting polymers, and offered bright and efficient LECs. Especially, a blue-emitting LEC showed excellent performance: the luminance reached ∼20 000 cd m-2 with a high luminance efficiency of ∼5 cd A-1, of which performances significantly exceed a light-emitting diode using the same polymer. The ionic liquid was further applied to the LECs with state-of-the-art light-emitting dendrimers showing thermally activated delayed fluorescence under electrical excitation, giving a high efficiency of 11 cd A-1. These demonstrations remind us of the great importance of the polymer-electrolyte compatibility and the usefulness of ILs for electrolyte of LECs.
AB - Light-emitting electrochemical cells (LECs) are composed of blends of semiconducting polymers and electrolytes, in which a unique cooperative action of ions and electrons induces a dynamic p-n junction for efficient emission. One of the crucial issues remaining in LECs is uniformity in blends of polymer and electrolyte; phase separation in between the two components results in poor performance or failure of operation. Here, we overcome this issue by developing an ionic liquid-based electrolyte of alkylphosphonium-phosphate that shows notable compatibility high enough to dissolve even light-emitting polymers. This exceptional compatibility enabled us to prepare uniform film blends with various blue to red emitting polymers, and offered bright and efficient LECs. Especially, a blue-emitting LEC showed excellent performance: the luminance reached ∼20 000 cd m-2 with a high luminance efficiency of ∼5 cd A-1, of which performances significantly exceed a light-emitting diode using the same polymer. The ionic liquid was further applied to the LECs with state-of-the-art light-emitting dendrimers showing thermally activated delayed fluorescence under electrical excitation, giving a high efficiency of 11 cd A-1. These demonstrations remind us of the great importance of the polymer-electrolyte compatibility and the usefulness of ILs for electrolyte of LECs.
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U2 - 10.1021/acs.chemmater.7b02128
DO - 10.1021/acs.chemmater.7b02128
M3 - Article
AN - SCOPUS:85025822401
VL - 29
SP - 6122
EP - 6129
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 14
ER -