Self-assembled monolayer modification of indium tin oxide anode surface for polymer light-emitting diodes with poly[2-methoxy-5-(2-ethylhexyloxy)-1,4- phenylene vinylene] for high performance

Abstract

We demonstrate that introducing a self-assembled monolayer (SAM) derived from 1,1,1,3,3,3-hexamethyldisilazane on an indium tin oxide (ITO) anode surface for the device (ITO/SAM/poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene]/ CaAl), can lead to an improvement in maximum device efficiency from 2.0 to 3.9 cdA and maximum brightness from 33 000 to 34 400 cd m2. Such improvement is even better than that with introducing a layer of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (2.6 cdA and 16 000 cd m2), which is usually used as a hole transport (or injection) layer. The improvement results from a hole blocking effect and better wetting by converting the ITO surface from hydrophilic to hydrophobic provided by the SAM. © 2005 American Institute of Physics.