An Effective Intermediate Al/Au Electrode for Stacked Color-Tunable Organic Light Emitting Devices

Bright and efficient stacked color-tunable organic light emitting devices (OLEDs) using intermediate Al/Au electrode have been reported. The effects of the thickness of Al and Au layer on the luminance characteristics have been comprehensively studied. After the optimization, After the optimization, the bottom-emission single-unit OLED of 4,4',4''-Tris(N-3-methylphenyl-N-phenyl-amino) triphenylamine /N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine /tris(8-hydroxyquinoline) aluminum has a maximum luminance efficiency (ηL) of 3.37 by using Al/Au as the cathode and 2.92 cd/A by using Al/Au as the anode. By introducing the optimized intermediate Al/Au electrode into the stacked color-tunable OLEDs, red unit with maximum ηL of 4.73 cd/A and blue unit with maximum ηL of 3.96 cd/A have been obtained. The color can be tuned efficiently along a linear route from pure red with the Commission Internationale de l'Eclairage (CIE) coordinates of (0.662, 0.330) to sky blue with the CIE coordinates of (0.155, 0.340). This scheme can be a potential candidate for achieving high brightness and efficient stacked color-tunable OLEDs