Double interfacial layers for highly efficient organic light-emitting devices

Abstract

The authors report on a highly efficient phosphorescent organic light-emitting device (PHOLED) achieved by introducing nanoscale double interfacial layers, made by ultrathin surfactant and low work-function metal layers. It is shown that double interfacial layers play multiple roles in the enhancement of device performance: increasing electron injection, hole blocking, and reducing surface roughness of electroluminescent layer. With double interfacial layers, a PHOLED has shown efficiency as high as ∼60cd∕A with a current density of 1.6mA∕cm2 and a luminance of 1000cd∕m2 at 6.5V, which is higher than that of a control device with a single CsF interfacial layer.