This thesis contains a study of polymer light emitting diodes (PLEDs) for commercial use
within blue organic light-emitting diode (OLED) display technologies. The introduction
chapter outlines the aims and synthetic strategies / targets employed during the research and
gives background information as to the historical development of OLEDs and PLEDs.
The first chapter of research involves the synthesis of several alternating co-polymers of
dibenzosilole (a previously reported monomer used in light emitting devices), along with the
prerequisite monomers. These co-polymers have been fully characterised and their optoelectronic
properties evaluated. The energy levels of the co-polymers (HOMO / LUMO)
were measured, then compared with each other and used to establish correlations between
these values and the use of co-monomers and the polymer backbone linearity. By tuning the
energy levels of conjugated polymers, it is possible to alter both the energy of the light
emitted (and therefore the colour) and also improve the charge-injection balance within the
OLED device, thereby improving lifetimes and performance. This research was primarily
concerned with blue light-emission, therefore these energy level studies were conducted with
a view to achieving blue light emission with the desired CIE coordinates and luminance. The
novel co-polymers were used to fabricate several prototype OLED devices and the
performance of these has been evaluated.
The second chapter of research contains a study of several novel silicon-containing
monomer structures, for incorporation into conjugated PLEDs. The first structure is a
disilaanthracene derivative and the attempted synthesis of this monomer is reported. The
other two monomers are based on spirosilabifluorene and the syntheses and full
characterisations are reported. Attempts at the coupling of these monomers were made, using
several different known coupling reactions including Suzuki, Stille and Kumada. The
attempted coupling products were simple trimers, using 9,9-dioctylfluorene as a co-monomer.
These were to be used in small molecule organic light-emitting diodes (SMOLEDs). The
outcomes of these coupling reactions are described.