Highly efficient tandem p-i-n organic light-emitting diodes adopting a low temperature evaporated rhenium oxide interconnecting layer

High quality interconnection units (ICUs) with a high transparency and superior charge generating capability for tandem organic light-emitting diodes (OLEDs) are developed. The ICUs of rubidium carbonate-doped 4,7-dipheny1-1,10-phenanthroline/rhenium oxide (ReO3)-doped N, N' -diphenyl-N, N' -bis (1,1' -biphenyl)-4, 4' -diamine layers with or without an additional ReO3 interlayer produce high transmittance (88%-92% at 420-700 nm) and spontaneous internal charge generation properties. A very high efficiency of similar to 129 cd/A has been demonstrated from only two stacked green p-i-n OLEDs by employing the developed ICUs. The relationship between the device efficiency and internal charge generation within the ICUs is further described by means of the capacitance measurements. (c) 2008 American Institute of Physics.