Creating novel thermally activated delayed fluorescence (TADF) emitters for light-emitting electrochemical cells (LEECs) and organic light-emitting diodes (OLEDs) applications and their structure-property relationship
Abstract
Developing organic light-emitting diodes (OLEDs) as the next generation
display devices is not only of industrial interest, but also a scientific challenge in and
of itself that requires multi-disciplinary efforts to make the technology successful.
Thermally activated delayed fluorescence (TADF) is a recent breakthrough in OLED
technology whose prime value is to enable purely organic emitters to recruit the dark
triplet excitons in the device, thus avoiding expensive and toxic rare metal based
emitters.
This thesis is centred on TADF and contains work in three major areas. Firstly,
novel ionic TADF emitters were designed for use in light-emitting electrochemical cells
(LEECs), which is an alternative electroluminescent device technology to OLEDs, with
a much simplified fabrication procedure and architecture. The vast majority of these
ionic emitters are based on reported TADF scaffolds where the donors were tethered
with an imidazolium hexafluorophosphate group to obtain the ionic character required
for LEEC devices (TL and BTL series, Chapter 2). On the other hand, TADF emitters
with a carboxylate group were also designed which act as both acceptor and intrinsic
charged functionality for LEEC applications (CTL series, Chapter 2). Secondly,
attempts were made to create novel TADF molecular scaffolds in order to enrich the
current library of TADF emitters. Research efforts were focused on polyaromatic
moieties such as anthracene (An series, Chapter 4) and fluoranthene (FA series,
Chapter 4) that are seldom reported in TADF literature. In addition, TADF emitters
with phosphine oxide as the acceptor group have also been studied (PO series, Chapter
5). Lastly, structure-property relationship studies of TADF emitters were undertaken as
a function of tuning of donor and acceptor functionalities using both theoretical and experimental approaches in order to gain more insight for designing desirable TADF
emitters (Chapter 3).
Type
Thesis, PhD Doctor of Philosophy
Rights
Embargo Date: 2020-08-23
Embargo Reason: Thesis restricted in accordance with University regulations. Print and electronic copy restricted until 23rd August 2020
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