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 20 for “"Shockley-Queisser limit"”.
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Beyond the Shockley-Queisser limit : intermediate band and tandem solar cells leveraging silicon and CdTe technology
… increasing and approaching their fundamental Shockley-Queisser efficiency limits. This is true for mature commercial technologies such as silicon and cadmium telluride. In order to enable solar cells with higher efficiency limits, new concepts need to be implemented which overcome the …
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Design and analysis of solar cells by coupled electrical - optical simulation
… high efficiency solar cells that approach the Shockley-Queisser limit, however, electrical and optical transports are tightly coupled in both directions. Photons generated by radiative recombination can be reabsorbed to create additional electron-hole pairs (so-called photon recycling), which …
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Patterned quantum dots for solar cell applications
The theoretical efficiency limit of current solar cell technology, called the Shockley-Queisser limit, is about 30%. Research is underway to overcome this limit using new types of nano-sized solar cells. Quantum dots offer the potential to increase the efficiency of solar cells through carrier …
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Photoluminescence Characterization of Patterned Quantum dots and Inverse Quantum dots
The ever increasing demand for oil and its limited supply have forced us to look for alternate sources of energy. Solar energy offers a cheap, alternate form of energy. The efficiency of a solar cell is set by the Shockley-Queisser limit and is currently very low. New techniques to increase the …
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Quantum efficiency and fission rate in tetracene
… the theoretical energy conversion efficiency limit is larger 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 …
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Spectroscopic Study of Triplet Exciton Dynamics at the Hybrid Organic-Inorganic Interface
… two spectral management mechanisms to break the Shockley–Queisser limit by overcoming the thermalisation and absorption losses inherent to all single-junction photovoltaics. Such spectral management technologies have been predicted to increase the maximum possible efficiency of Si-based cells …
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Understanding electronic defects in organic solar cells: Defect identification, characterization & mitigation
… efficiencies exceeding 13%, but with the Shockley-Queisser limit calculated at 21% for single-junction cells, there are many facets left for improvement. Recombination and mobility deficits are considered two of the largest bottlenecks in organic solar cells – accounting for 50-60% of …
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Singlet exciton fission, a multi-exciton generation process, in organic semiconductor solar cells
… singlet exciton fission, to work around the Shockley-Queisser limit, according to which, all single junctions cells have a theoretical efficiency limit of 33.7%. This is the first implementation of a singlet fission photovoltaic. We measured a singlet fission efficiency of 72% at room …
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Theoretical characterisation of spheroidal PbSe/PbS Core/Shell colloidal quantum dot heterostructures
… of conventional solar cell (SC) devices is limited to ∼ 31% (Shockley-Queisser limit), devices based on NQDs may attain a maximal thermodynamic efficiency of 42% through the exploitation of multiple exciton generation (MEG). In this process, several electron-hole pairs are created by the …
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Modulated Magnetic Field Effects, Molecular Design, and Indigoids: A Mechanistic Study of Singlet Fission
… harvesting of silicon solar cells beyond the Shockley-Queisser limit. The progress of this technology has been hindered by the limited selection of suitable molecules that can undergo singlet fission, and the methods we use to screen new materials. This thesis is constructed in two parts: the …
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Singlet Fission in Pechmann Dyes and Molecular Oligomers
… photovoltaic efficiencies, surpassing the Shockley-Queisser limit. Two major challenges, however, are (i) finding suitable material systems and (ii) improving the triplet exciton lifetimes for harvesting. This thesis addresses these questions and presents a new molecular design strategy, …
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Modeling tin sulfide grain growth during post-processing
… efficiency of approximately 32% according to the Shockley-Queisser limit (Shockley, Queisser, 1961). However, the efficiency of most SnS systems is around 4% in low sun conditions (Hartman, 2011). To understand how to improve this efficiency, further research is being done on the grain structure …
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Electronic Structure Modelling of Singlet Fission in Organic Photovoltaics
… future photovoltaic devices, by overcoming the Shockley-Queisser limit. In spite of considerable experimental and theoretical attention, different aspects of the process are still not fully understood. The main reason for this is that singlet fission is characterised by a complex interplay of …
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Applications of spectral management in optoelectronic devices
… devices and offers the potential to break the Shockley-Queisser limit. Here we present solar cells fabricated from PbSe nanorods which show external quantum efficiencies exceeding 100 %. This demonstrates the potential for substantial improvements in PV device performance due to MEG. Through …
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Quantum Coherence and Entanglement in Open Quantum Systems
… can break the detailed balance, the key factor limiting the efficiency in artificial solar cells. By mimicking photosynthetic complexes, a designed solar cell taking advantage of coherent donors caused by dipole-dipole interactions is able to achieve a higher energy conversion efficiency than …
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Materials, photophysics and device designs for high efficiency photovoltaics
… candidate in the renewable energy market. The Shockley-Queisser limit (S-Q limit), also known as the detailed balance limit, refers to the maximum theoretical efficiency that can be achieved using a single p-n junction solar cell. Silicon PVs, which account for about 90% of the solar-PVs market …
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Synthesis and Optical Characterisation of Diphenylhexatriene Derived Intramolecular Singlet Fission Materials
… One key assumption underlying the theoretical Shockley-Queisser limit of the efficiency of photovoltaic devices is that the absorption of one photon can only produce a single electron-hole pair; all excess energy above the bandgap of the semiconductor is lost to thermalisation. Singlet fission …
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Multisource Evaporation of Perovskite Solar Cells
… a promising route to exceed the single-junction Shockley–Queisser limit. A wide bandgap perovskite with bandgap from 1.62 eV to 1.8 eV, fabricated by multisource evaporation, is explored by controlling the PbBr2 evaporation rate. The photoluminescence, time-resolved photoluminescence and phase …
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Interfacial engineering and spectroscopy of spin-triplet excitons for singlet fission sensitization of silicon solar cells
… 25 years as they ap- proach their thermodynamic limit. Thermalization of high-energy photons is the single largest energy loss process in these devices, accounting for the loss of a third of all incident solar energy. Singlet exciton fission, an energy-splitting process that converts single …
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Investigation of the Synthesis and Optoelectronic Properties of Ultrasmall CdSe Quantum Dots
… generation, solar cells have a theoretical upper limit of 33% power conversion efficiency based on the thermodynamic limitation of the single p-n junction cell design. This limitation is known as the Shockley-Queisser limit and methods to design solar cells to circumvent it have been creative, …