Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"triplet exciton"”.
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Triplet exciton dynamics in conjugated polymer films
… for efficient use of these novel materials. Triplet excitons are believed to play an important role in conjugated polymer-based device operation. Triplet excitons are also believed to play a primary role in photo-oxidative degredation of polymer devices. Two-photon photoemission is used to …
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Triplet Exciton Management in Organic Electronic Devices
… diodes and organic photovoltaics. Tightly-bound excitons form intermediate states in the operation of both organic light-emitting diodes and organic photovoltaics. Many properties of an exciton are determined by its spin state, which can either be a spin-zero singlet or a spin-one triplet. In …
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Triplet Exciton Management via Solid-State Interactions in Organic Semiconductors
Tightly-bound excitons play an important role in the function of molecular materials for light emission and light harvesting. This thesis investigates the effects of solid-state interactions on triplet excitons in a new family of organometallic light emitters, carbene-metal-amides (CMAs). Triplet …
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Triplet-Exciton Pairs in Organic Crystals: Optical Properties of TIPS-tetracene
Contains fulltext : 331368.pdf (Publisher’s version ) (Open Access)
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Spectroscopic Study of Triplet Exciton Dynamics at the Hybrid Organic-Inorganic Interface
The control and utilisation of spin-triplet excitons in organic semiconductors is highly sought after for the next generation of Optoelectronic applications. Of particular interest is the utilisation of these photoexcited states in the singlet-fission photon-multiplier and triplet-triplet …
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Study of Triplet Exciton Dynamics in Small Organic Molecule Films Using Time Resolved Optical Spectroscopy
… years it has become clear that knowledge of triplet transport in single layer and multilayer films can be crucial in improving the efficiency of organic light emitting devices and solar cells. This thesis reports an investigation of triplet exciton dynamics in small organic molecule single …
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The Role of Triplet Exciton Lifetime in the Stability and Efficiency of Blue Phosphorescent OLEDs Or Why Even The Brightest OLEDs Have a Dark Side
… in devices due to the existence of long-lived triplet excitons believed to be a crucial source of molecular damage and efficiency loss. Most modern AMOLED displays, to this day, employ high-efficiency phosphorescent OLEDs in red and green pixels, whereas blue emission is still realized by their …
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Controlling Triplet Excitons in Organic Semiconductors with Lanthanide-Doped Nanoparticles
… performance of these materials is governed by excitonic processes, in which electronically excited states mediate light absorption, emission, and charge generation. Triplet excitons play a central role in determining the excited-state dynamics of OSCs under both optical and electrical …
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Development in utilizing singlet fission and triplet-triplet annihilation to improve solar cell efficiency
… warming. In this thesis, singlet fission and triplet-triplet annihilation would be discussed and studied to increase solar cell power conversion efficiency. Singlet fission splits a singlet exciton into two lower energy triplet excitons. This energy down conversion is efficient and have shown …
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Delayed fluorescence as a probe of radiationless transitions in anthracene and algae
… which is qualitatively explained in terms of triplet exciton traps. The delayed fluorescence emitted by algae is explained in terms of a triplet exciton fusion model in which the production of triplets is mediated by a photochemical reaction center (photosystem II). The evidence for this model …
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Quantum efficiency and fission rate in tetracene
… than the Shockley-Queisser limit due to two excitons produced with one incident photon. In a singlet fission material, an absorbed photon excites a singlet exciton and then split into two triplet excitons with energy around half of the singlet exciton. Tetracene is a potential candidate for …
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Modeling the chemical and photophysical properties of gold complexes.
… thus ground state models of the corresponding triplet AuIL3. The disproportionation of AuIIL3 to AuIL3 and AuIIIL3 is endothermic for all ligands investigated, however, σ-donors are better experimental targets for AuII complexes. For dimeric AuI complexes, only one gold center in the optimized …
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Design and construction of instruments for exciton diffusion characterization and for patterning of thin films
… devices. One instrument characterizes exciton diffusion and the other patterns organic thin films. Exciton diffusion characteristics are important to study in organic materials because excitons mediate the transport of energy. In this work, a fluorescence microscope is designed and …
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Triplet Excitons in Natural Photosynthetic and Artificial Light Harvesting Systems: Measurement and Modeling.
… oxygen (1O2) by energy transfer from the (B)Chl triplet state (3(B)Chl) to the oxygen ground state. Natural photosynthetic systems must protect themselves from 1O2, typically done by positioning carotenoids within a few angstroms of each (B)Chl molecule to quench 3(B)Chl states. Using …
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Singlet Fission Organic Solar Cell with Long-Wavelength Absorption Using Non-fullerene Acceptors
Organic solar cells made with singlet exciton fission materials are able to convert a single photon into two charges. Paired with a long-wavelength absorbing acceptor material, singlet fission materials enable solar cells that exhibit the quantum efficiency benefits of a multi-junction solar cell, …
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Removing the Spin-Triplet Loss Pathway in Organic Solar Cells: A Strategy to Enhance Radiative Efficiency and Minimise Energy Loss
… our work into suppressing the formation of triplet excitons in organic solar cells, created as a result of unavoidable non-geminate charge recombination processes. Triplet excitons represent a major non-radiative loss pathway in organic solar cells and through this work, we demonstrate …
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Singlet exciton fission : applications to solar energy harvesting
Singlet exciton fission transforms a single molecular excited state into two excited states of half the energy. When used in solar cells it can double the photocurrent from high energy photons increasing the maximum theoretical power efficiency to greater than 40%. The steady state singlet fission …
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Characterization of Local field effect in organic film using pressure technique
… the effects of local dielectric changes on the excitonic energy levels in amorphous organic thin films for optoelectronic device applications. Compression of organic films causes a decrease in intermolecular spacing and, through solvation effects, lowers the exciton transition energy. A series …
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Electrical and magnetic properties of organic semiconductors: Electrical conductivity and electron spin resonance studies of semiconducting, organic, charge transfer salts.
… The ESR spectra of these salts are attributed to triplet excitons showing that the spin-spin and electronelectron correlation effects are important. In the ESR spectra (Chapter III) of some TCNQ salts dipolar splitting is observed confirming the spin-spin interaction. These triplet excitons are …
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Singlet Fission in Pechmann Dyes and Molecular Oligomers
… whereby a high-energy photoexcited singlet exciton converts to two low-energy triplet excitons through a spin-conserving pathway. When integrated into photovoltaics, singlet fission offers the opportunity to mitigate thermalization losses and possesses the potential to improve …
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