Efficient Non-Doped Blue Electro-fluorescence with Boosted and Balanced Carrier Mobilities

One of the most important issues of the organic light-emitting diode (OLED) is the highly efficient blue-emissive material, which demands both excellent photoluminescent quantum yield (PLQY) and balanced carrier mobilities. Herein, a series of blue-emissive donor-pi-acceptor (D-pi-A) materials with fluorene pi-bridge and their D-A analogues are synthesized and discovered with a theoretical combined experimental method. Based on the excellent electron mobility of the oxadiazole (OXZ) acceptor, it is further proven that the insertion of the fluorene pi-bridge can not only contribute to the formation of hybrid local and charge-transfer excited state with high PLQY, but also give rise to the hole mobilities by enhanced intermolecular face-to-face stacking. As a result, the non-doped OLED of TPACFOXZ exhibits a high maximum external quantum efficiency approaching 10% with boosted and balanced hole and electron mobilities of 5.60 x 10(-5) and 6.60 x 10(-5) cm(2) V-1 s(-1), respectively, which are among the best results of the non-doped blue fluorescent OLEDs.

Automated summary

One of the most important challenges in organic light-emitting diodes (OLEDs) is the development of highly efficient blue-emissive materials. In this study, a series of blue-emissive materials with donor-pi-acceptor (D-pi-A) structures containing a fluorene pi-bridge were synthesized and investigated. It was found that the insertion of the fluorene pi-bridge not only promoted the formation of hybrid local and charge-transfer excited states with high photoluminescent quantum yield (PLQY), but also enhanced hole mobilities through intermolecular face-to-face stacking. As a result, the non-doped OLED using TPACFOXZ achieved a high maximum external quantum efficiency of nearly 10% with balanced hole and electron mobilities.