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

Abstract

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-diphenyl-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 420–700nm) and spontaneous internal charge generation properties. A very high efficiency of ∼129cd∕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.