Bright white polymer double-layer LEDs

A white polymer light emitting diode (LED) from a double-layer structure consisting of a hole transport layer emitting in red and blue emissive layer doped with a green fluorescent dye is studied. The three distinctive emissions, blue, green, and red comprise the white emission (CIE, 0.34, 0.36). This white polymer LED has a brightness of 600 Cd/m2 at 16 V and a maximum external quantum efficiency of 0.13%. The white light emission in these LEDs is generated by spectral superposition due to the partial energy transfer from the blue emitting polyfluorene to the green Py546, which, in turn, is transferred partially to the red emitting transport layer.