Silicon Heterojunction Solar Cells: The Key Role of Heterointerfaces and their Impact on the Performance

This chapter is dedicated to the processes linked with the collection of photo-generated carriers in silicon heterojunction (SHJ) solar cells with a focus on the key role of the amorphous silicon/crystalline silicon heterojunction. The intention is to explain the role of carrier inversion at the heterointerface and connect it with the properties of the SHJ to obtain deeper understanding of carrier transport properties and collection, which goes beyond amorphous silicon-based structures and will contribute to understanding the new emerging SHJ based on amorphous silicon oxide and metal oxide emitter layers. The study is extended by a simulation of the TCO/emitter interface with the aim to reveal the effect of parasitic Schottky barrier height on the performance of the SHJ solar cell. In addition, the simulation study of SHJ under concentrated light and varied temperatures is outlined to show the main limitations and prospects of SHJ structures for utilization under concentrated light

AP-MOVPE Technology and Characterization of InGaAsN p-i-n Subcell for InGaAsN/GaAs Tandem Solar Cell

Tandem (two p-n junctions connected by tunnel junction) and multijunction solar cells (MJSCs) based on AIIIBV semiconductor compounds and alloys are the most effective photovoltaic devices. Record efficiency of the MJSCs exceeds 44% under concentrated sunlight. Individual subcells connected in series by tunnel junctions are crucial components of these devices. In this paper we present atmospheric pressure metal organic vapour phase epitaxy (AP-MOVPE) of InGaAsN based subcell for InGaAsN/GaAs tandem solar cell. The parameters of epitaxial structure (optical and electrical), fabrication process of the test solar cell devices and current-voltage (J-V) characteristics are presented and discussed

Podnikatelský záměr s možností rozšíření zemědělské farmy

The aim of the bachelor thesis is to analyze the current state of the selected agricul-tural farm (family business Mikolášek) and to suggest the possibilities of its ex-pansion. The work is divided into 3 main parts: theoretical part, own work and ap-pendices. The theoretical part of the thesis deals with the analysis of the business environment and acquaints the reader with the basic concepts and information that are needed to know and understand business and its forms. The current state of the agricultural farm and the actual implementation of the business plan based on com-pany analyzes and investments are presented in the thesis. The conclusion contains an evaluation of the entire business plan

A Facile Two-Step PVP-Assisted Deposition of Co-Activated Nanosized Nickel Hydroxide Directly on a Substrate for Large-Scale Production of Supercapacitor Electrodes

The self-decomposition reaction of the nickel ammonia complex was used for the nickel hydroxide formation on the nickel foam with further modification in several ways. The addition of polyvinyl pyrrolidone (PVP) and the electrochemical or chemical activation with cobalt hydroxide was used to modify the formation method. In all cases, structures with Ni(OH)2 nanoflakes were formed. It was found that the flower-like particles of Co(OH)2 were precipitated during chemical activation among the nanoflakes. It was shown that the presence of PVP during the nickel ammonia complex decomposition suppressed the highly branched particles. The absence of the highly branched particles increased the capacitive properties of the formed electrode at high current densities. The highest capacitance in 1408 F/g at 1 A/g was shown for the sample precipitated with the PVP presence and the further chemical activation by cobalt

Structure and Thermal Stability of ε/κ-Ga₂O₃ Films Deposited by Liquid-Injection MOCVD

We report on crystal structure and thermal stability of epitaxial ε/κ-Ga2O3 thin films grown by liquid-injection metal–organic chemical vapor deposition (LI-MOCVD). Si-doped Ga2O3 films with a thickness of 120 nm and root mean square surface roughness of ~1 nm were grown using gallium-tetramethylheptanedionate (Ga(thd)3) and tetraethyl orthosilicate (TEOS) as Ga and Si precursor, respectively, on c-plane sapphire substrates at 600 °C. In particular, the possibility to discriminate between ε and κ-phase Ga2O3 using X-ray diffraction (XRD) φ-scan analysis or electron diffraction analysis using conventional TEM was investigated. It is shown that the hexagonal ε-phase can be unambiguously identified by XRD or TEM only in the case that the orthorhombic κ-phase is completely suppressed. Additionally, thermal stability of prepared ε/κ-Ga2O3 films was studied by in situ and ex situ XRD analysis and atomic force microscopy. The films were found to preserve their crystal structure at temperatures as high as 1100 °C for 5 min or annealing at 900 °C for 10 min in vacuum ambient (2O3 and possible amorphization of the films

Elektro – optický monitoring citrátu sodného aplikovatelného v hemodialýze

V této práci se popisují naše počáteční experimenty ve vývoji „on-line“ senzoru na monitoring koncentrace citrátu sodného (Na3C6H2O7) v mimo mozkovém proudění krve v průběhu hemodialýzy. Přesný a rychlý monitoring by umožnil regulaci koncentrace citrátu a návrat do krevního řečiště těla v jeho původních hodnotách, tím pacienta významně méně zatíženého než v přítomnosti. Nedávno jsme se soustředili na stanovení koncentrace měřením elektrické impedance a odrazivosti ve zkoumané krvi. Našim cílem je zkoumat trendy vlivu těchto signálů na koncentraci a vyvinout vhodnou metodiku, která může být použita později v senzorech. Částečně začínáme pracovat také na citlivosti metodiky, přičemž bychom rádi výpočtem dosáhli ekvivalentní elektrický model řešení. To je založeno na elektrochemickém dvouvrstvém modelu a korespondenci s Cole-Cole grafyIn this paper, we describe our initial steps in the development of online sensor to monitor the tri-sodium citrate concentration in extra-cerebral blood flow during haemodialysis. Accurate and fast monitoring would allow the regulation of the concentration of citrate returning to the human bloodstream to its original values, thereby, making the patient significantly less burdened than at present. In the early stages, we focused on the determination of concentration by measuring of electrical impedance and reflection in the collected blood. Our aim is to study the trends of influencing these signals by concentration and to develop a suitable methodology that can be used later in the sensor. In part, we begin working on the selectivity of the methodology that we would like to achieve by calculating the equivalent electrical model of the solution. It is based on the electrochemical double layer model and the corresponding Cole-Cole graphs

Raman spectroscopy of silicon with nanostructured surface

We compared the morphology and Raman response of nanoscale shaped surfaces of Si substrates versus monocrystalline Si. Samples were structured by reactive ion etching, and four of them were covered by a RuO2-IrO2 layer. Raman bands, centred at approx. 520 cm–1, belonging to samples processed by etching the Si surface have intensities higher by approximately one order of magnitude than those of reference non-etched samples. For nanostructured samples, the rise in the Raman signal was 12–14 ×, which is in agreement with the model of the electric field at the tips of Si due to their geometry. This phenomenon is related to the high absorption of excitation radiation. Nanostructured surfaces of samples containing a layer of RuO2-IrO2 give rise to the phenomenon of surface enhancement of the Raman response most likely due to the charge transfer at the interface between silicon and conductive oxides. The nanostructured surface of Si without a metal layer behaves as a SERS substrate and detects the analytes at a low concentration.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Photovoltaic Materials and DevicesElectrical Sustainable Energ