Organic light-emitting diodes and photovoltaic devices: Incorporation of carbon nanotubes as charge transport media

Abstract

The effects of incorporating multi-walled carbon nanotubes (MWNT) in two existing functional organic devices : organic light emitting diodes (OLEDs) and organic solar cells have been studied. Single layer OLEDs and organic photovoltaic devices were firstly prepared and characterised in order to understand the physics of conjugated polymers based organic devices without the use of MWNT. Careful analysis of the device's characteristics of a single layer OLED allowed us to determine the intrinsic electronic parameters (Fermi energy level, majority charge carriers' mobility, ...) of one the main conjugated polymers used throughout this Thesis: poly(2,5-dimethoxy-l,4phenylenevinylene-2-methoxy-5(2'-ethylhexyloxy)-1,4-phenylenevinylene (M3EH-PPV). As regards single layer polymer solar cells, we found that only a very thin layer was photoactive, resulting in power efficiency being greater for thinner polymer solar cells.