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

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]/Ca∕Al), can lead to an improvement in maximum device efficiency from 2.0to3.9cd∕A and maximum brightness from 33000to34400cd∕m2. Such improvement is even better than that with introducing a layer of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (2.6cd∕A and 16000cd∕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.