| Abstract [eng] |
The study of organic semiconductors has got significant attention due to their unique potential and associated challenges. These materials, predominantly composed of carbon-based small molecules or polymers, exhibit distinct advantages over conventional inorganic semiconductors, including intrinsic flexibility, cost-efficient production processes, and solution-processability. Such characteristics position organic semiconductors as ideal candidates for applications in flexible displays, wearable electronics, and biodegradable sensors. A critical focus in this field lies in the efficient manipulation of excitons — electron-hole pairs within semiconductors, which is central to optimizing their performance in optoelectronic applications. Despite these advances, the effective utilization of excitons for light emission remains a fundamental challenge. Among the most promising approaches to address this issue is triplet harvesting, a technique that facilitates the conversion of non-emissive triplet excitons into emissive singlet excitons, thereby enhancing theoretical internal quantum efficiency (IQE) from 25% to nearly 100%. This dissertation systematically investigates three distinct triplet harvesting mechanisms: thermally activated delayed fluorescence (TADF), triplet-triplet annihilation (TTA), and hybridized local and charge-transfer excited states (HLCT). These mechanisms have been crucial in enabling organic light-emitting diodes (OLEDs) to achieve external quantum efficiencies exceeding 25%, marking a significant advancement in the field of organic optoelectronic devices. |
