Solution processable single layer organic light-emitting devices with a single small molecular ionic iridium compound

摘要

We herein report on the occurrence of bright and efficient electrophosphorescence from a simple organic light-emitting diode (OLED) with a single organic layer comprised of a small molecular ionic iridium compound, formed using a solution process. The studied small molecular ionic iridium compound is [Ir(dfppy)_2(bpy)]+PF_6~-, which exhibits excellent film-forming properties, bright green photoluminescence, and efficient bipolar carrier transport with balanced electron and hole mobilities of about 10~(-5) cm~2/ (V s). A high performance of the device was achieved by using a phosphorescent OLED (PHOLED) that was fabricated using the [Ir(dfppy)_2(bpy)]+PF_6~- compound, with a peak brightness of about 18 000 cd/m~2 and a peak current efficiency of 12 cd/A. A peak power efficiency of 2.5 lm/W was measured at 2800 cd/m~2. These results suggest that the small molecular ionic iridium compound is a promising material for bright and efficient PHOLEDs manufactured using a simple solution process.