Synthesis of spiro[fluorene-9,9'-xanthene] derivatives and their application as hole-transporting materials for organic light-emitting devices

摘要

A series of hole-transporting molecules based on spiro(fluorene-9,9'-xanthene) were designed and synthesized by a copper-catalyzed modified Ullmann reaction. These compounds have very high-lying HOMO levels (～5.0eV), which are beneficial for the hole-injection from 1T0 anode. The double-layer EL devices using DPA-SFXMe and DPA-SFXBu as hole-transporting layers exhibit lower turn-on voltage and higher efficiency compared with those of a typical NPB-based device. The DPA-SFXBu-based device exhibits high maximum luminescence of 21,712 cd/m~2, and its power efficiency can reach a value of 2.311m/W, which is nearly 90% higher than that of a similar NPB-based device.