@phdthesis{Sperlich2013, author = {Sperlich, Andreas}, title = {Electron Paramagnetic Resonance Spectroscopy of Conjugated Polymers and Fullerenes for Organic Photovoltaics}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-81244}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2013}, abstract = {In the presented thesis, the various excited states encountered in conjugated organic semiconductors are investigated with respect to their utilization in organic thin-film solar cells. Most of these states are spin-baring and can therefore be addressed by means of magnetic resonance spectroscopy. The primary singlet excitation (spin 0), as well as positive and negative polaronic charge carriers (spin 1/2) are discussed. Additionally, triplet excitons (spin 1) and charge transfer complexes are examined, focussing on their differing spin-spin interaction strength. For the investigation of these spin-baring states especially methods of electron paramagnetic resonance (EPR) are best suited. Therefore according experimental methods were implemented in the course of this work to study conjugated polymers, fullerenes and their blends with continuous wave as well as time-resolved EPR and optically detected magnetic resonance.}, subject = {Organische Solarzelle}, language = {en} } @phdthesis{Vaeth2016, author = {V{\"a}th, Stefan Kilian}, title = {On the Role of Spin States in Organic Semiconductor Devices}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141894}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2016}, abstract = {The present work addressed the influence of spins on fundamental processes in organic semiconductors. In most cases, the role of spins in the conversion of sun light into electricity was of particular interest. However, also the reversed process, an electric current creating luminescence, was investigated by means of spin sensitive measurements. In this work, many material systems were probed with a variety of innovative detection techniques based on electron paramagnetic resonance spectroscopy. More precisely, the observable could be customized which resulted in the experimental techniques photoluminescence detected magnetic resonance (PLDMR), electrically detected magnetic resonance (EDMR), and electroluminescence detected magnetic resonance (ELDMR). Besides the commonly used continuous wave EPR spectroscopy, this selection of measurement methods yielded an access to almost all intermediate steps occurring in organic semiconductors during the conversion of light into electricity and vice versa. Special attention was paid to the fact that all results were applicable to realistic working conditions of the investigated devices, i.e. room temperature application and realistic illumination conditions.}, subject = {Organischer Halbleiter}, language = {en} } @phdthesis{Bunzmann2021, author = {Bunzmann, Nikolai Eberhard}, title = {Excited State Pathways in 3rd Generation Organic Light-Emitting Diodes}, doi = {10.25972/OPUS-22078}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-220786}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {This work revealed spin states that are involved in the light generation of organic light-emitting diodes (OLEDs) that are based on thermally activated delayed fluorescence (TADF). First, several donor:acceptor-based TADF systems forming exciplex states were investigated. Afterwards, a TADF emitter that shows intramolecular charge transfer states but also forms exciplex states with a proper donor molecule was studied. The primary experimental technique was electron paramagnetic resonance (EPR), in particular the advanced methods electroluminescence detected magnetic resonance (ELDMR), photoluminescence detected magnetic resonance (PLDMR) and electrically detected magnetic resonance (EDMR). Additional information was gathered from time-resolved and continuous wave photoluminescence measurements.}, subject = {Elektronenspinresonanz}, language = {en} } @phdthesis{Gruene2022, author = {Gr{\"u}ne, Jeannine}, title = {Spin States and Efficiency-Limiting Pathways in Optoelectronic Materials and Devices}, doi = {10.25972/OPUS-29340}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293405}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2022}, abstract = {This thesis addresses the identification and characterization of spin states in optoelectronic materials and devices using multiple spin-sensitive techniques. For this purpose, a systematic study focussing on triplet states as well as associated loss pathways and excited state kinetics was carried out. The research was based on comparing a range of donor:acceptor systems, reaching from organic light emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) to organic photovoltaics (OPV) employing fullerene and multiple non-fullerene acceptors (NFAs). By developing new strategies, e.g., appropriate modeling, new magnetic resonance techniques and experimental frameworks, the influence of spin states in the fundamental processes of organic semiconductors has been investigated. Thereby, the combination of techniques based on the principle of electron paramagnetic resonance (EPR), in particular transient EPR (trEPR) and optically detected magnetic resonance (ODMR), with all-optical methods, such as transient electroluminescence (trEL) and transient absorption (TA), has been employed. As a result, excited spin states, especially molecular and charge transfer (CT) states, were investigated in terms of kinetic behavior and associated pathways, which revealed a significant impact of triplet states on efficiency-limiting processes in both optoelectronic applications.}, subject = {Elektronenspinresonanz}, language = {en} } @phdthesis{Weissenseel2022, author = {Weißenseel, Sebastian G{\"u}nter}, title = {Spin-Spin Interactions and their Impact on Organic Light-Emitting Devices}, doi = {10.25972/OPUS-25745}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257458}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2022}, abstract = {This work investigates the correlations between spin states and the light emission properties of organic light-emitting diodes (OLEDs), which are based on the principle of thermally activated delayed fluorescence. The spin-spin interactions responsible for this mechanism are investigated in this work using methods based on spin-sensitive electron paramagnetic resonance (EPR). In particular, this method has been applied to electrically driven OLEDs. The magnetic resonance has been detected by electroluminescence, giving this method its name: electroluminescence detected magnetic resonance (ELDMR). Initial investigations on a novel deep blue TADF emitter were performed. Furthermore, the ELDMR method was used in this work to directly detect the spin states in the OLED. These measurements were further underlined by time-resolved experiments such as transient electro- and photoluminescence.}, subject = {Elektronenspinresonanz}, language = {en} }