형광물질을 적용한 2개의 발광층을 가진 백색유기발광소자의 제작과 광학적 특성

F abrication and O ptical characteristics of \Vhite O rganic L ig ht- em itting Diodes using fluorescence m aterials w ith tw o em issive layers

White organic light-emitting diodes (WOLEDs) with multi-emissive layer structure using two color fluorescent materials is fabricated. WOLED device is composed of ITO / NPB (50nm) / DPVBi (6.5nm) / MADN ： DCM2 - 0.5% (17nm) / Bphen (30nm) / Liq (2nm) / Al (lOOnm). DCM2 was functioned as red fluorescent dye under MADN of red host material while DPVBi worked as blue emitting material in this structure. To obtain best white CIE color coordinate of (0.33 ， 0.33)，thicknesses of DPBVi and MADN was changed as varying DCM2’s concentration according to color shift in EL spectra. Optimized WOLED device shows emission efficiency of 5.04 cd/A, current density of 18.6 mA/cm2 and luminance of 940 cd/m2 at 6 V with CIE color coordinate, (0.34, 0.33). These results indicates that DPVBi layer effects on hole blocking and control of the exciton due to difference of energy level in highest occupied molecular orbital.