Red Fluorenes as the Efficient Host Emitter for Non-Doped Red Organic Light-Emitting Diodes

摘要

Crystallinic red fluorophores based on donor-acceptor substituted spirofluorene, I.e., PhSPDCV show strong fluorescence in solution ( Φf ~ 70 %) as well as in solid state ( Φf > 30 %). Non-doped red OLEDs fabricated with PhSPDCV exhibit Authentic red (CIE, x = 0.65, y = 0.35) electroluminescence with brightness over 12,000 cd m-2 (or > 600 cd m-2 at 20 mA cm-2) and remarkable external quantum efficiency as high as 3.6%. On the other hand, the bis-substituted derivatives of spirofluorene BisPhSPDCV show relatively weak fluorescence both in solution ( Φf < 20 %) and in solid state ( Φf < 10 %). Although saturated red electroluminescence (CIE, x = 0.65, y = 0.35) is observed, non-doped red OLED containing BisPhSPDCV exhibit much worse performance compared with that of PhSPDCV OLEDs.