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.
Results
Showing 1 to 15 of 15 for “"exciton dissociation"”.
-
The role of spatial size and orientation of electronic wavefunction in exciton dissociation at van der Waals interfaces
… are generated directly by the light absorption, excitons, Coulombic bound electron-hole pairs, are created upon light absorption in OPV materials. The performance of OPVs depends on how effective the bound charge transfer (CT) exciton, an exciton with its electron and hole spatially separated by …
-
The application of photosynthetic materials and architectures to solar cells
… photosynthetic reaction center is the site of exciton dissociation in photosynthesis, analogous to the role of the donor-acceptor interface in organic PV. This thesis describes the successful integration of reaction centers with organic semiconductors into solid-state devices. Although …
-
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, …
-
The Role of Disorder in the Charge Dissociation and Recombination Processes of Organic Photovoltaic Materials
… interfacial driving forces in determining the dissociation free energy of an electron/hole pair. With proper statistical treatment of the CT energies we recover experimentally observed ''hot'' and "cold'' exciton dissociation pathways. We also recover experimental values for the open-circuit …
-
Photoluminescent quantum-dot light emitting devices controlled by electric field induced quenching
… induced quenching in our devices is due to exciton dissociation and reduced band-edge exciton formation at high field strengths. The resulting QD PL device exhibits voltage-controlled PL quenching up to 99.5%, corresponding to a high contrast ratio of 200:1, and a sub-microsecond response …
-
Optical spectroscopy of conjugated polymers.
… to model the behaviour of the photogenerated exciton after excitation. At the same time, the . probing sheds light on the mechanisms at work in the deceleration of the implanted ions and the nature and location of the damage produced. A study of the effect of applied electrical field on the …
-
Photosynthesis-inspired device architectures for organic photovoltaics
… (1) a trade-off between light absorption and exciton diffusion and (2) low open-circuit voltage due to charge recombination at the donor-acceptor interface. In this work, we demonstrate two new device architectures inspired by photosynthesis that aim to overcome these two challenges. First, we …
-
Nanocarbons as charge carriers in organic solar cells
… shorted MWNTs provide larger surface area for exciton dissociation and better phase separation and probably lead to less charge recombination. Therefore, they show higher PCE. Functionalized nanodiamonds (ND) are also introduced to C60 to synthesize C60-ND-COOH composite by taking the advantage …
-
Enhanced Charge Transport and Cell Performance of an Inverted Organic Solar Cell Via UV-ozone Treatment of ZnO
… additional interfacial area provided by ZnO for exciton dissociation. Future work should address increasing the charge carrier concentration of the ZnO film by dopants, and improving active layer morphology by using additives such as DIO.</p>
-
Exciton behaviour at organic solar cell interfaces
… donor-acceptor interfacial surface area where excitons are split apart to create free charges. The generation of free charges after photo-excitation is a main factor influencing solar cell efficiency. However, the mechanisms of charge transfer and the competing process of charge recombination …
-
Ultrafast Spectroscopic Studies of Solution-Processing Organic Photovoltaic Materials and Devices
… acceptors (NFAs). Firstly, the rate of exciton dissociation is studied in state-of-the-art organic blends with NFAs. The charge generation is found to be slow (ps), in sharp contrast with the ultrafast timescales in traditional blends based on fullerene acceptors. Secondly, a new …
-
Design and Characterization of Electrospun Mats with Tailored Morphologies for Enhanced Active Layer Performance in Energy Conversion and Energy Storage Applications
… of the active layer morphology can promote exciton dissociation in organic photovoltaic cells (OPVs), whereas developing efficient ion diffusion pathways and beneficial polymer-ion interaction in polymer-gel electrolytes is demonstrated to result in enhanced battery performance. We …
-
Novel materials, computational spectroscopy, and multiscale simulation in nanoscale photovoltaics
… formation of strongly bound electron-hole pairs (excitons) upon photoabsorption requiring the presence of semiconductor heterointerfaces within the active layer to dissociate excitons and generate charge carriers. Such interfaces are known as donor-acceptor (D-A) interfaces, and their presence …
-
High-Speed Organic Photodetectors for Visible Light Communication
… semiconductors. This structure enables quick exciton dissociation and efficient charge collection at the appropriate electrodes. State-of-the-art unique modelling, simulation and experimental studies are conducted. The work extensively explores the fabrication equipment and structure of an …
-
Understanding and engineering interfacial charge transfer of carbon nanotubes and graphene for energy and sensing applications
… bound electron-hole pair, also known as an exciton. Excitons can decay via radiative or non-radiative recombination or by colliding with other excitons. They can diffuse along the length of a SWCNT or hop from larger band gap SWCNTs to smaller band gap SWCNTs, a process known as exciton …