Static and dynamic simulations of photoprocesses in organic phosphorescent and thermally activated delayed fluorescent materials
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Date
2023
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Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2023.
Abstract
The development of organic phosphorescent and thermally activated delayed fluorescence (TADF) emitters have emerged as potential candidates for high efficiency organic light-emitting diodes (OLEDs). The common design strategy of both organic phosphorescent and thermally activated emitters is their purely organic structures which provides an opportunity to develop environmentally friendly, low-cost devices with high device efficiencies. Investigation of working mechanisms and design strategies of all electronic devices is important to develop high efficiency technologies. In organic phosphorescent materials, device efficiencies have been increased with the radiative decay observed from the T1 to S0 state. On the other hand, efficiency of TADF materials is mainly controlled by the reverse intersystem crossing (RISC) between T1 and S1 states which leads to the harvesting of generated triplet excitons. In this thesis, experimentally synthesized TADF and room temperature organic phosphorescence materials (oRTP) with various structural properties were modeled to investigate the photophysical processes in their working mechanisms. In the first part, a general benchmark study has been performed on a wide range of TADF emitters with various structural properties. The purpose of this general study was exploring the well performing computational protocol for further, more specific theoretical analyses. In the second and third part of this thesis, boron-based and sulfone-based TADF emitters were analyzed in detail and the role of boron and sulfone containing acceptor moieties on RISC efficiency have been explored. These studies provide a unique perspective on the underlying mechanism of photoprocesses in TADF devices.