Highly power efficient organic light-emitting diodes based on Cs₂CO₃n-doped and MoO₃p-doped carrier transport layers

Abstract

We demonstrate highly efficient Alq3-based p–i–n organic light-emitting diodes by using cesium carbonate (Cs2CO3)-doped 4'7-diphyenyl-1, 10-phenanthroline (Bphen) as an electron transport layer, and by using molybdenum trioxide (MoO3)-doped N, N'-diphenyl-N, N'-bis(1,1'-biphenyl)-4,4'-diamine (NPB) as a hole transport layer, which could significantly enhance the electron injection and transport, resulting in a large increase in luminance and efficiency. The maximum luminance, current efficiency and power efficiency reach 23 420 cd cm−2, 6.4 cd A−1 and 5.3 lm W−1, respectively, which are much higher than those of the referenced device (without doping). This improvement is attributed to the improved conductivity of the transport layers and the efficient charge balance in the emission zone.