We report the use of green and blue fluorene conjugated polymers doped with
hole transport materials consisting of triarylamine copolymers to fabricat
e bright and efficient blue and green single-layer light-emitting diodes (L
EDs). These blends show enhanced quantum and power efficiency, much higher
brightness and current densities and lower turn on and operating voltages c
ompared with undoped devices. Optimised blue emission devices exhibited a m
aximum brightness of 1550 cd/m(2), a maximum external electroluminescence q
uantum efficiency of 0.9 cd/A or 0.4% and a maximum power efficiency of 0.3
lm/W. Optimised green emission devices showed a maximum brightness of 7400
cd/m(2), a maximum external electroluminescence quantum yield of 0.9% or 2
.75 ed/A and a maximum power efficiency of 0.64 lm/W at high brightness. (C
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