Higher efficiency conjugated polymer-based LEDs by control of polymer filmmorphology and interchain interactions

Aggregation of conjugated polymer chains in optoelectronic devices promotes good carrier transport but quenches luminescence, leading to a fundamental trade-off in optimizing film morphology for applications. Changing the sol ution from which a conjugated polymer film is cast can control the degree o f aggregation in the film. In this paper, we show that the efficiency of li ght-emitting diodes (LEDs) based on poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4 -phenylenevinylene) (MEH-PPV) can be improved by constructing tri-layer dev ices, which use a central MEH-PPV layer with reduced interchain interaction s between layers of more highly aggregated MEH-PPV near the electrodes.