Carrier transport and recombination of white organic light-emitting diodes

Homojunction structure involved p/n-doped layers in the organic charge transport layers of organic light-emitting diodes (OLEDs) was developed to achieve chromaticity-tunable white OLEDs. This structure based on a single-layer structure which had a bipolar host material and co-dopant of complementary blue and yellow emitters, A relatively low turn-on voltage of 5.6 V, a high current efficiency of 2.64 cd/A and a low efficiency roll-off were achieved. Moreover, the Commission Internationale dEclairage coordinates varied from (0.41, 0.43) to (0.32, 0.35), which shifted almost along with the Planckian locus as the luminance increased. In addition, the charge carrier transport properties and recombination mechanisms were investigated and analyzed.