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A quantum dot model is constructed for nanofillers inside polymer nanocomposites. This is a versatile model to explain all dielectric characteristics of polymer nanocomposites. Permittivity reduction, threshold for space charge formation, and exciton annihilation are discussed based on this model.
Quantum dot (QD)-based solar cells have been the subject of over two decades of research with the hopes of increasing their efficiency to surpass single junction solar cells. To date, no single working device has been developed that surpasses the efficiency of a single junction solar cell. Fundamental issues including unrealistic assumptions involved in theoretical work, tendency of stretching observed...
Thermalisation and below-bandgap loss mechanisms of intermediate band solar cells (IBSCs) comprised of InAs(1−x)Nx quantum dots (QDs) embedded within intrinsic layer of AlP0.5Sb0.5 p-i-n solar cell is calculated. a Finite element method is used for solving Schrödinger equation to calculate possible energy band configurations of AIP0.5Sb0.5: barrier/InAs(1−x)Nx: square pyramid-shaped QDs with different...
The proposed work explains the absorption property of different material which can be used for the formation of Quantum Dot and their use in solar cells. By using property of Intermediate Band Gap of Quantum Dot efficiency of solar cells can also be increased. Along with it, it's found that absorption of Quantum Dot Depends on the angle by which light falls on them and in most of the cases its maximum...
Improving the efficiency of the third generation solar cells, containing semiconductor quantum dots (QD) as components, is associated with the obtaining of nanoparticles with controlled parameters. Micellar synthesis method has certain advantages providing the obtaining of nanoscale monodisperse particles. In the reverse emulsion of bis (2-ethylhexyl) sodium sulfosuccinate (AOT)/n-hexane/water the...
According to the Bloch theorem and the symmetry of superlattice configuration, a new 3D finite element method is employed to calculate the miniband structure and density of state for well-aligned Ge/Si QDs array. This method can overcome the approximation of multi-dimensional Kronig-Penny model and constrain on QDs superlattice structure. The interaction of electronic structure among Ge/Si QDs with...
The search for higher efficiencies in photovoltaics has led us to develop increasingly complex solar cell architectures that rely on increasingly complex physical processes. The desire to overcome the Shockley-Queisser efficiency limit has caused us to consider stacks of junctions with cascading bandgaps, quantum dots and impurities for the creation of intermediate bands, amongst others. The need...
This article presents a computational study on the impact of layer distance on the miniband formulation and density of state under different quantum dot structural parameters-height, interdot space-in a bilayer and well-aligned Ge/Si quantum-dot array. The miniband bandwidth, energy and effective bandgap is tunable by introducing an additional quantum dot layer. When the vertical distance between...
Light emitting III–V materials have shown a severe reduction in efficiency for wavelengths in the range 550–590 nm in both InGaN and AlInGaP compounds. Quantum dot (QD) based active layer could afford the promise to solve some of these limitations, providing an interesting route towards high performance optoelectronic devices emitting in the yellow band. Here we investigate the photoluminescence properties...
In this age of miniaturization and nanotechnology, nano sized zero dimensional particles called quantum dots are finding wide range applications. The reasons behind their growing popularity are their controllable electrical and optical properties. This control is achieved by tuning their bandgaps by changing their shape and size. But quantum effects are most prominent only within strong confinement...
Use of renewable energy is the key to produce electricity from limited resources. Solar cells appear as promising candidates for this purpose. Research on third generation quantum dot solar cells have drawn much attention. Solar cells made of wide bandgap materials that utilize quantum dots have the potentials for being ideal solar cells of future. Quantum dots have a tunable bandgap, so they can...
Photoelectric effect using two photon processes is a new research area interest that referrers to science and technology fields to find out new solar cells. In this review article focuses on examining light-matter interaction in quantum processes which are directly or indirectly related to the photoelectric effect and highlighting recent research results. This model is used as a tool to understand...
In this work, an efficient method is applied to calculate the miniband structure and density of states for well-ordered Ge/Si quantum dot (QD) array fabricated by combining the self-assemble bio-template and damage-free neutral beam etching. Within the envelop-function framework, this computational model surmounts theoretical approximations of the multi-dimensional Kronig-Penney method and the numerical...
We present a computational model for predicting the net solar energy conversion efficiency of a single-junction solar cell backed by a solid-state photon upconversion nanostructure. We model the upconversion process using a series of kinetic rate equations to calculate equilibrium populations. We determine the upconversion quantum efficiency (UQE) of the proposed device as a function of intentionally...
We present simulations of InAs QDs embedded in AlAsSb, which may be a promising candidate system for realizing intermediate band solar cells as it features bandgaps close to the ideal and a nearly flat type-II valence band lineup. We have also experimentally investigated InAs quantum dots (QDs) grown in an AlAs0.56Sb0.44 matrix in the unintentionally doped (uid) region of an In0.52Al0.48As solar cell...
This paper reports one-pot method toward the synthesis of CuInS2/ZnS hybrid nanoparticles. First, CuInS2 quantum dots (QDs) were synthesized in the noncoordinating solvent octadecene using copper chlorine, indium chlorine and dodecanethiol. Copper indium sulfide (CIS) quantum dots (QDs) for different Cu/In molar ratios of 1/1, 1/2, and 1/4 are synthesized. The band gap energy of CIS QDs is observed...
Photoluminescence properties of the low-dimensional semiconductor nanostructures of materials with indirect electronic band gap are studied theoretically with an emphasis put on the coupling of charge carriers to the atomic lattice vibrations. The photoluminescence intensity decay time dependence, the temperature dependence of the photoluminescence as well as the dependence of the photoluminescence...
Multiple, serially-connected nanoscale rings are analyzed using a tight-binding computational algorithm which allows calculation of the transmission and current characteristics of the system as a function of energy and external magnetic flux. Results show the role of bilateral symmetry in the system response to imposed flux, which can shift the system from metallic to semiconducting.
InxGa1−xN/GaN quantum dot intermediate band solar cell (QD-IBSC) is a promising candidate for the purpose of efficiency improvement of solar cells. In this work, the influences of interdot distance, quantum dot size and indium content of InxGa1−xN/GaN QD-IBSC on the position and width of the intermediate bands are investigated by solving Schrödinger equation using Kronig-Penney model. Finally the...
We performed photoluminescence and radiative lifetime measurements of quantum dots (QDs) showing different carrier dynamic mechanisms at elevated pressures that could reveal the inter-QD coupling as the QDs spacing decreases with increasing hydrostatic pressure.
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