A terpyridine-modified chrysene derivative as an electron transporter to improve the lifetime in phosphorescent OLEDs†
In this work, we designed and developed a terpyridine-modified chrysene derivative, abbreviated as B3TPyC, to be used as electron-transport layers (ETLs) toward the construction of highly stable phosphorescent OLEDs. A green phosphorescent OLED with a B3TPyC ETL exhibited a low turn-on voltage of 2.4 V at 1 cd m−2 and an external quantum efficiency of 17.5% at 1000 cd m−2 with a long operation lifetime at 50% of the initial luminance (LT50) of over 258 h at current density 25 mA cm−2 (an initial luminance of approximately 12 000 cd m−2), which corresponds to a LT50 of 19 000 h at 1000 cd m−2. This is more than 1.5 times longer than the time of luminance decay provided by the phenylpyridine counterpart named B3PyPC. These results clearly show the potential and usefulness of terpyridine-based chrysene derivatives to be applied in high-performance OLEDs with high operational stability.