2017年春修士修了 柄澤太一郎君のリチウム錯体電子注入材料に関する
「A Series of Lithium Pyridyl Phenolate Complexes with a Pendant Pyridyl Group for Electron-Injection Layers in Organic Light-Emitting Devices」
と題する論文がアメリカ化学会 (ACS) のACS Applied Materials & Interfaces (IF: 7.504) に受理されました。末端ピリジンの置換位置の異なる３種のビピリジルフェノラート配位子を持つリチウム錯体を有機EL素子の電子注入材料に応用し、置換位置の差異がどのように素子性能に影響を与えるのかを議論しました。
柄澤 太一郎君、一緒に実験を行ったD3 渡邊 雄一郎君、M1 大澤 達矢君、おめでとうございます！
本研究中のGIWAXD測定は、東原 知哉先生、東原研究室D3 福田 斉二郎氏、JASRI/SPring-8の小金澤智之 博士、M2 早坂 裕哉君のご協力のもと行われました。ありがとうございました！
By Satoru Ohisa*, Taichiro Karasawa, Yuichiro Watanabe, Tatsuya Ohsawa, Yong-Jin Pu, Tomoyuki Koganezawa, Hisahiro Sasabe, Junji Kido*,
ACS Applied Materials & Interfaces, 2017, 9, 40541-40548.
Abstract: We report a new series of lithium pyridyl phenolate complexes with a pendant pyridyl group, Li2BPP, Li3BPP, and Li4BPP, in which the pendant pyridines are substituted at the 2-, 3-, and 4-positions, respectively. The most important difference between these complexes is their molecular planarity; Li3BPP and Li4BPP adopt twisted bipyridine structures, whereas Li2BPP adopts a planar structure owing to the steric hindrance and chelating effect of bipyridine on the Li core. The planar structure leads to crystallization through p–p stacking interactions, and the small differences in the molecular structures of the pendant pyridine rings cause drastic differences in the physical properties of thin solid films of these complexes. We applied these complexes as electron-injection layers (EILs) in Ir(ppy)3-based organic light-emitting devices. When thin EILs were used, Li3BPP and Li4BPP afforded lower driving voltages than Li2BPP; the order of the driving voltages followed the order of their electron affinity values. Moreover, the dependence of driving voltage on the EIL thickness was investigated for each complex. Among the three LiBPP derivatives, Li2BPP-based devices showed almost negligible EIL thickness dependence, which may be attributable to the high crystallinity of Li2BPP. All LiBPP-based devices also showed higher stability than conventional 8-quinolinolato lithium-based devices.
