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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 29 for “"exciton binding"”.
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Absorption and emission processes in organometal trihalide perovskites
… properties assumed that perovskites exhibit excitonic properties, feature typical of organic materials. On the contrary, recent optical spectroscopy reports converge to state that the majority of band-edge optical excitations at room temperature are free carriers, as it happens in inorganic …
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Electronic and optical properties of semiconductor quantum wells
… the mixing effects on valence subband structure, exciton binding energies and oscillator strengths, and absorption spectra is undertaken using a multiband effective mass method which takes valence subband mixing into account. In addition the method is extended to study uniaxial stress and …
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Development and Application of Explicitly Correlated Wave Function Based Methods for the Investigation of Optical Properties of Semiconductor Nanomaterials
… dot systems including the effect of dot size on exciton binding energy and recombination probability in a CdSe quantum dot, the effect of shape on a CdSe quantum dot, the effect of heterojunction on a CdSe/ZnS quantum dot and the effect of quantum dot-biomolecule interaction within a CdSe-firefly …
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Optical absorption measurements on silver halides in the ultraviolet and extreme ultraviolet energy ranges
… estimated from the ultraviolet energy data and exciton binding energies. Comparison of ultraviolet structure and extreme ultraviolet structure, and measurements taken at different temperatures give evidence that in the high energy region exciton absorption is insignificant compared to absorption …
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Excitons in the thallous halides
… absorption features have appeared and exciton effects have been established. A variety of experiments were performed to clarify the nature of the structure associated with the first exciton peak. Intrinsic structure and structure due to strain lifted degeneracy has been identified. …
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First principles calculations on ZnO non-equilibrium phase
… Further, by solving the Bethe-Salpeter Equation, excitonic effect has been included and the exact optical spectrum for both structure has been obtained. We have found a large optical anisotropy for BN structure. Lastly we calculated the exciton binding energy for the BN phase and have found a …
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Photostabilization of J-aggregate cyanine dyes for exciton-polariton based devices
… strongly coupled systems as they possess large exciton binding energies and huge oscillator strengths that have allowed for the creation of room temperature polariton condensates, superfluids, and other exotic phenomena. Using J-aggregates, the aggregated form of cyanine organic dyes, we have …
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Temperature dependent excitonic effects in silicon
The exciton binding energy and phonon energies are the two key parameters in defining the bandgap energy of a semiconductor. A more accurate measurement of bandgap energy can be obtained by adding the excitonic binding energy and the corresponding phonon energy to the optically measured threshold. …
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Experimental Interrogation Of One-Dimensional Excitons In Cadmium Selenide And Cadmium Telluride Quantum Nanostructures
… coulombic interaction between photo-generated excitons, and therefore increase the exciton binding energy as compared to bulk and quantum well structures. In this thesis, excitons in single one-dimensional CdSe and CdTe QWs were investigated using a combination of optical microscopy techniques. …
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Development of explicitly correlated and many-body diagrammatic techniques for the investigation of electron-hole correlation in nanomaterials
… that only linked diagrams contribute to the exciton binding energy. The approximation is made to only include rst order diagrams which captures the essential physics of the electron-hole interaction. In the composite control-variate stratied sampling (CCSS) method the calculation of the …
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Approaching Novel Perovskites Photovoltaic Devices through Machine Learning and Interfacial Engineering
… of perovskite largely take credit to their low exciton binding energy, strong light absorption coefficient, relatively long carrier diffusion length, and carrier recombination lifetime [6-9]. However, even with an increasing number of studies carried out, perovskite solar cell is still facing …
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Optical Characterization of Electrochemically Self-Assembled Compound Semiconductor Nanowires
… sample diameter. The 50 nm ZnO nanowires show an exciton recombination peak and an additional peak related to the deep trap levels. 25 nm ZnO nanowires show a only the exciton recombination peak, which is red shifted, possibly due to quantum confined Stark effect associated with built in charges …
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Plasma Treatment of Zinc Oxide Thin Film and Temperature Sensing Using the Zinc Oxide Thin Film
… wide bandgap, II-VI semiconductor. It has large exciton binding energy, large piezoelectric constant, strong luminescence, and high thermal conductivity. These properties make zinc oxide as a suitable material for various optoelectronic applications. Vacuum based processes of fabrication of zinc …
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Engineering nanocarbon interfaces for electron transfer
… and the fullerene LUMO levels are less than the exciton binding energy of the SWCNT in these two systems. In contrast, the lipid-C 85-PEG derivative shows complete quenching of all SWCNT species utilized in this work. This enhancement in quenching efficiency is consistent with the fact that the …
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Study of Moisture and Water Effects in Low Temperature Crystallization of Perovskite Film for Efficient Solar Cells
… low bandgap, long charge diffusion length, low exciton binding energy and balanced charge transport. The semiconducting perovskite films are typically prepared from low temperature solution processing and the corresponding solar cells have exhibited power conversion efficiency (PCE) of more than …
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Syntheses and Photophysical Studies of Two-Dimensional Hybrid Organic-Inorganic Semiconductors
… relationships, and the understanding of their exciton physics. In this thesis, we first present cooling-induced crystallization to produce phase-pure 2D LHPs with controllable chemical compositions. Using single-crystal X-ray diffraction, we refined their crystal structures across temperatures …
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Computational investigation on polycyclic aromatic hydrocarbons in the molecular and solid phases
… gap,optical absorption,excitonbindingenergy, and molecular reorganization energies for holesand electrons.For thispart of thework we used the hybrid exchange-correlation functional B3LYP in conjunction with a Gaussian localized basis-set.This adopted combination …
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Development and Application of Effective Stochastic Potential Method for Investigating Temperature-dependent Electronic Properties of Nanomaterials
… HOMO-LUMO gap energies, excitation energies, and exciton binding energies comprised of a million samples. For many of the systems studied, calculation of these distributions using traditional first-principle methods would be infeasible. Using the ESP method, it has been calculated that the …
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Synthesis, Properties and Applications of Micro/Nano Zinc Oxide Spheres
… optical properties, such as wide bandgap, high exciton binding energy at room temperature, and high refractive index. These properties can lead ZnO material to the applications of electronics and optoelectronics. More importantly, the realization of various kinds of ZnO micro- or …
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Exciton Dynamics and Anisotropy in 2D Metal Organochalcogenolate Semiconductors
… (MOCs). Since its blue-emitting excitonic properties were discovered in 2018, AgSePh has attracted attention from the scientific community. From a fundamental science perspective, AgSePh provides an excellent platform for exploring many-body interactions among quasiparticles (such …
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