Efficient single-layer "twistacene"-doped polymer white light-emitting diodes

Bright, efficient, and stable white polymer light-emitting diodes based on blue polyfluorene doped by a "twistacene," 6, 8, 15, 17-tetraphenyl-1.18, 4.5, 9.10, 13.14-tetrabenzoheptacene ( 3 ) (TBH), are demonstrated. In "twistacene" the terminal pyrene moieties serve two functions: (i) to stabilize the inherently unstable heptacene and (ii) to enable the oligoacene to be a strongly fluorescent molecule. As a result, efficient and very bright white polymer light-emitting diodes are obtained. The maximum luminance of the devices exceeds 20 000 cd ∕ m 2 . The maximum luminous efficiency is 3.55 cd ∕ A at 4228 cd ∕ m 2 while the maximum power efficiency is 1.6 lm ∕ W at 310 cd ∕ m 2 . The device obtains a stable white balance by a combination of energy transfer from the blue polyfluorene to TBH by 1% TBH doping plus the host emission. The device emission color is not a function of bias current, which is ideal for various applications, from lighting to the backlight for liquid crystal displays.