M2 大澤達也君と笹部久宏准教授のイミダゾール誘導体を利用した水色TADF発光材料群に関する「A Series of Imidazo[1,2-f]phenanthridine-Based Blue-to-Sky-Blue TADF Emitters Realizing EQE of over 20%」と題する論文が Wiley の Advanced Optical Materials (IF: 7.43) に受理され、2019年3月5日号の Back Cover に選出されました。大澤、おめでとう！大澤くんデザインのカバーイラストを見てやって下さい。
Title: A Series of Imidazo[1,2-f]phenanthridine-Based Sky-Blue TADF Emitters Realizing EQE of over 20%
By T. Ohsawa, H, Sasabe*, R. Komatsu, K. Nakao, Y. Hayashi, Y. Hayasaka, T. Watanabe, J. Kido*, Adv. Opt. Mater. 2019, 7, 1801282.
Abstract: Although imidazole derivatives are promising as blue fluorescent emitters in organic light-emitting devices (OLEDs), the corresponding blue thermally activated delayed fluorescence (TADF) emitter is rarely explored. In this study, we have developed a series of imidazo[1,2-f]phenanthridine-based TADF materials in the blue-to-sky blue region. The resultant benzimidazole (BIP)-based TADF materials, with p-expanded acceptor and electron-donor phenoxazine (PXZ), namely PXZ-BIP, showed a high maximum external quantum efficiency (EQEmax) of 21% with CIE coordinates of (0.21, 0.37). To the best our knowledge, these results have clearly demonstrated that PXZ-BIP exhibited the highest EQEmax among imidazole-based fluorescent sky-blue OLEDs. The corresponding imidazophenanthridine (IP) derivative, with a less p-expanded acceptor, showed inferior OLED performances, with an EQEmax of 5.9% and CIE of (0.19, 0.30). This study provides a critical molecular design to realize high efficiency TADF materials based on imidazole derivatives.
