Study of Deep Blue Organic Light-Emitting Diodes Using Doped BCzVBi with Various Blue Host Materials

Abstract

Deep blue organic light emitting diodes (OLEDs) were fabricated using 5 wt.% doped BCzVBi with various blue host materials such as NPB, DPVBi, MADN and TPBi. A blue OLED device, using DPVBi as host material, was constructed via NPB (<TEX>$500\;{\AA}$</TEX>) / DPVBi:BCzVBi (<TEX>$200\;{\AA}$</TEX>) / Bphen (<TEX>$300\;{\AA}$</TEX>) / LiF (<TEX>$20\;{\AA}$</TEX>) / Al (<TEX>$1,000\;{\AA}$</TEX>) and it shows a maximum luminescence of <TEX>$4,838\;cd/m^2$</TEX>, a current density of <TEX>$32.7\;mA/cm^2$</TEX>, a luminous efficiency of 3.3 cd/A and CIExy coordinates of (0.19, 0.15) at 4.5 V whereas the luminous efficiencies and CIExy coordinates of other blue OLEDs using NPB, MADN and TPBi as host materials have 1.1, 2.6 and 2.0 cd/A and (0.15, 0.11), (0.15, 0.10) and (0.15, 0.10), respectively. Energy transfer mechanisms between BCzVBi and its host materials were discussed with an energy band structure of host materials.