White organic light-emitting diode comprising of blue fluorescence and red phosphorescence

Abstract

A white organic light-emitting diode with the structure of ITO∕NPB30nm∕TCTA+2%TPP20nm∕BCP+0.4%Ir(piq)320nm∕Alq340nm∕Mg:Ag was fabricated and characterized, where 2,5,7,10-tetra-phenylpyrene and tris(1-phenylisoquinoline) iridium (III) [Ir(piq)3] were used as a blue fluorescent dye and a red phosphorescent dye respectively. The I–V characteristics of the device showed a turn-on voltage of 2.6 V. The electroluminescent spectra of the device consisted of blue fluorescent and red phosphorescent emissions. The intensity of the blue emission increased gradually relative to the red emission with increasing voltage. The emissions of the device were in the white-light region between 10 and 15 V. A maximum white light luminance of 1076cd∕m2 with CIE coordinates of (x, y=0.27, 0.24) was reached at 15 V with an efficiency of 1.35cd∕A. The white light emission is related to the simultaneous exciton formation on both sides of the TCTA/BCP interface.