Three main-chain aromatic polyethers with different electroactive hete
rocyclic moieties, 1,4-quinoxaline, 1,3,4-oxadiazole and 1,3,5-triazin
e, have been synthesized. The polymers are amorphous with glass transi
tion temperatures above 200 degrees C. The polymers with these high el
ectron affinity units were used as hole blocking/electron transport la
yers (HBETL) in light-emitting diodes (LEDs) having the HBETL casted o
n top of a hole transport/emitting PPV layer. In order to compare the
influence of the different polyethers on the LED characteristics, thre
e multilayer devices (ITO/PPV/HBETL/Al) with different HBETLs were inv
estigated. Relative to the single layer PPV device, quantum efficienci
es were improved by two orders of magnitude in all multilayer devices
and power efficiency was increased using poly(quinoxaline ether) as HB
ETL. To investigate the electrochemical behavior of the three HBETLs,
cyclic voltammetry measurements were carried out and the HOMO/LUMO ene
rgy values determined from redox potentials were used to understand th
e hole blocking property. Lowering the onset voltage using the poly(qu
inoxaline ether) as HBETL in two-layer devices is compatible with the
high electron affinity of this polymer.