Enhanced performance of white organic light-emitting devices based on ambipolar white organic single crystals

Organic single crystals are highly promising for applications in optoelectronic devices because of their higher mobility and thermal stability than amorphous thin films. Although white organic single crystals have been fabricated by the double-doped method and applied to realize white organic light-emitting devices (WOLEDs), the unbalanced carrier transport properties of the unipolar crystals severely limit the device performance. Here, ambipolar white organic single crystals are obtained by using mixed p- and n-type molecules as an ambipolar host for the red and green dopants. The white crystal with balanced carrier transport and balanced blue, green, and red emission intensity was applied to the single-crystal WOLEDs. The highest brightness of 1956cd m(-2) and the current efficiency of 1.31cd A(-1) are achieved, which are the best performance of the single-crystal WOLEDs reported to date. A high color rendering index is obtained, which varies between 82 and 87 with increasing driving current. It is expectable that this strategy would support the practical applications of organic single crystal-based OLEDs.

Automated summary

By using mixed p- and n-type molecules as an ambipolar host for red and green dopants, ambipolar white organic single crystals with balanced carrier transport and emission intensity were obtained. These single-crystal WOLEDs achieved the highest brightness and current efficiency reported to date, along with a high color rendering index that varied with increasing driving current. This strategy is expected to support practical applications of organic single crystal-based OLEDs.