M2 佐藤守悟君 (Mr. Shugo Sato) の大気安定・低電圧・高効率有機ELを実現する疎水性ポリイオン液体電荷注入材料に関する「Air-Stable and High-Performance Solution-Processed Organic Light-Emitting Devices Based on Hydrophobic Polymeric Ionic Liquid Carrier Injection Layers」と題する研究論文が Wiley の Advanced Materials (IF: 19.79) に受理されました。ポリジアリルジメチルアンモニウムと疎水性アニオンであるビストリフルオロメタンスルホニルイミドからなるポリイオン液体を電子注入層として用いた塗布型黄色蛍光高分子有機ELデバイスで、外部量子効率9.0 %、電流効率30.1 cd/A、電力効率 32.4 lm/Wを実現しています。また、正孔注入層として用いた有機ELデバイスでも、既存の正孔注入材料PEDOT:PSSと並ぶ性能を発揮します。さらに疎水性高分子であることから、大気下に置いた時にも安定です。屈折率測定を行っていただいた横山先生、一緒に研究を進めてくれた皆様、ありがとうございました！
By Shugo Sato, Satoru Ohisa,* Yukihiro Hayashi, Ryo Sato, Daisuke Yokoyama, Tetsuya Kato, Michinori Suzuki, Takayuki Chiba, Yong-Jin Pu, Junji Kido,* Adv. Mater. 2018, 1705915
Abstract: Many researches mostly using electron injection layers (EILs) composed of alkali metal compounds have been reported to increase the efficiency of solution-processed organic light-emitting devices (OLEDs). However, these materials have intractable properties, such as a strong affinity for moisture, which cause the degradation of OLEDs. Consequently, optimal EIL materials should exhibit high electron injection efficiency as well as be stable in air. In this study, we experimentally and analytically investigated the commonly used yellow-fluorescent emitting polymer F8BT-based polymer light-emitting devices (PLEDs) that utilize poly(diallyldimethylammonium)-based polymeric ionic liquids. As a result, the optimized PLED employing an EIL comprising poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (poly(DDA)TFSI), which is expected to display good moisture resistance because of water repellency of fluorocarbon groups, exhibits excellent storage stability in air and electroluminescence performance with a low turn-on voltage of 2.01 V, maximum external quantum efficiency of 9.00%, current efficiency of 30.1 cd/A, and power efficiency of 32.4 lm/W. Our devices with poly(DDA)TFSI showed one of the highest efficiency as compared to the reported standard PLEDs. Moreover, poly(DDA)TFSI was applied as an hole injection layer (HIL). The optimized PLED using poly(DDA)TFSI as the HIL exhibited performances comparable to those of a device that uses a conventional poly(3,4-ethylenedioxy-thiophene):poly(4-styrenesulfonate) HIL.
