Solar panels use the photovoltaic effect to convert sunlight into electricity by exciting electrons in silicon or other semiconductor materials. The electricity generated can power homes, buildings, spacecraft, and more. Research on solar cells won Einstein the Nobel Prize and continued improvements aim to increase the contribution of solar power to global energy needs.
Welcome new students to the university. An orientation will be held on Monday November 3rd for new students to familiarize themselves with campus, meet faculty and staff, and learn about available resources and support services. The goal is to help new students transition successfully to university life.
Solar cells convert sunlight into electricity through the photovoltaic effect. They are composed of silicon or silicon compounds and are an important area of renewable energy research. The power output of a solar cell can be measured using a voltmeter, ammeter, and light source. Readings from these devices along with the power equation allow determining the cell's power and efficiency by accounting for losses and dividing output power by input power from sunlight. While useful for powering satellites, solar cells face challenges on Earth from variable sunlight and the large surface area needed to generate significant electricity.
Optical spectroscopy allows the study of light-matter interactions and provides information about electronic structures. It is a key technique used to probe various states of matter. Spectroscopy gives direct information about electronic structures through the absorption and emission of radiation. Measurement of absorption and photoluminescence emission spectra provides information about electronic band structures and transition rates in semiconductors.
Briefing for the RSA International Solar Challenge. Delivered by Rob Treharne on Thurs 25 Feb 2016 @ 11am, Stephenson Institute for Renewable Energy, University of Liverpool
The document outlines a 3-day course on fundamentals of photovoltaics. Day 1 covers the history of solar cells, the photovoltaic effect, the AM1.5 solar spectrum, ideal diode equations, J-V curves, quantum efficiency and parasitic resistances. Day 2 focuses on semiconductors, junctions and their characterization. Day 3 discusses materials stability, optical properties, characterization techniques and current/future PV technologies, with an exam scheduled for Day 4.
Solar panels use the photovoltaic effect to convert sunlight into electricity by exciting electrons in silicon or other semiconductor materials. The electricity generated can power homes, buildings, spacecraft, and more. Research on solar cells won Einstein the Nobel Prize and continued improvements aim to increase the contribution of solar power to global energy needs.
Welcome new students to the university. An orientation will be held on Monday November 3rd for new students to familiarize themselves with campus, meet faculty and staff, and learn about available resources and support services. The goal is to help new students transition successfully to university life.
Solar cells convert sunlight into electricity through the photovoltaic effect. They are composed of silicon or silicon compounds and are an important area of renewable energy research. The power output of a solar cell can be measured using a voltmeter, ammeter, and light source. Readings from these devices along with the power equation allow determining the cell's power and efficiency by accounting for losses and dividing output power by input power from sunlight. While useful for powering satellites, solar cells face challenges on Earth from variable sunlight and the large surface area needed to generate significant electricity.
Optical spectroscopy allows the study of light-matter interactions and provides information about electronic structures. It is a key technique used to probe various states of matter. Spectroscopy gives direct information about electronic structures through the absorption and emission of radiation. Measurement of absorption and photoluminescence emission spectra provides information about electronic band structures and transition rates in semiconductors.
Briefing for the RSA International Solar Challenge. Delivered by Rob Treharne on Thurs 25 Feb 2016 @ 11am, Stephenson Institute for Renewable Energy, University of Liverpool
The document outlines a 3-day course on fundamentals of photovoltaics. Day 1 covers the history of solar cells, the photovoltaic effect, the AM1.5 solar spectrum, ideal diode equations, J-V curves, quantum efficiency and parasitic resistances. Day 2 focuses on semiconductors, junctions and their characterization. Day 3 discusses materials stability, optical properties, characterization techniques and current/future PV technologies, with an exam scheduled for Day 4.
A 2 hour fun and interactive workshop for students at the University of Liverpool that introduces the use of Microsoft Teams as a professional tool for collaborative working.
This document provides an overview of an interactive session on science and the read/write web for students. It introduces the inventor of the world wide web, Tim Berners-Lee, and his vision for a collaborative social web. It discusses the evolution of the web from a static read-only version 1.0 to the current more dynamic and social version 2.0. The session plan involves students using Slack for communication, Google Docs and Slides for collaborative creation of presentations on assigned topics, and SlideShare to publish their work to the wider web.
Optical spectroscopy techniques such as transmission, reflection, absorption, and photoluminescence measurements are important tools for characterizing the optical properties of semiconductor materials for photovoltaic applications. These techniques can determine the band gap type and energy, which are crucial for a material's suitability as a solar cell absorber. A direct band gap is preferable to an indirect band gap. Temperature-dependent absorption measurements provide insight into the temperature dependence of the band gap and allow comparison to density functional theory calculations. Characterizing defects through photoluminescence is also useful. Together, optical measurements provide essential information for understanding and improving photovoltaic materials.
This document discusses how solar cells work by using sunlight to create an electrical imbalance between n-type and p-type materials through the transfer of energy from photons to electrons, allowing the cells to generate electricity that can then be inverted for use.
The document discusses various solar cell technologies, including their world record efficiencies. It covers traditional silicon technologies, as well as thin-film technologies like CIGS and CdTe. Emerging technologies discussed include perovskites, dyes, organics, and multi-junction cells. For each technology, it provides the strengths and weaknesses, example efficiency levels, and sometimes a diagram. It aims to give an overview of both established and new concepts in photovoltaics.
1. The document discusses phase diagrams and thermodynamics of mixing.
2. It explains how phase diagrams can be used to determine the number and types of phases present, the composition of each phase, and the amount of each phase at a given temperature and composition.
3. Binary eutectic and eutectoid systems allow for a range of microstructures depending on the cooling rate, and alloying generally increases strength but decreases ductility due to solid solution strengthening.
An introduction to the fundamental physics of transparent conducting oxides including a review of the electrical and optical properties of common materials.
A Combinatorial Approach to the Optimisation of Cd (1−x) Zn x S Layers for Cd...University of Liverpool
A combinatorial methodology has been adopted to determine the optimum composition of a Cd ( 1 − x)Zn x S window
layer for CdTe solar cells. The methodology generated a large, self
consistent dataset which permitted an unambiguous relationship
between x, conversion efficiency and related cell parameters to
be determined. An optimum composition of x = 0.57 was shown
to maximise cell efficiency. Analysis of J − V curves, measured
over 72 separate cells show that both short circuit current, J SC ,
and fill factor, F F , values increase with respect to x over the
range 0.1−0.57. EQE measurements show that further increases
in J SC value are limited by the band gap of the highly resistive
transparent (HRT) ZnO layer. The methodology demonstrates a
rapid route, compared to conventional experiments, to the further
optimisation of CdTe solar cells.
A low-cost non-toxic post-growth activation step for CdTe solar cellsUniversity of Liverpool
Cadmium telluride, CdTe, is now firmly established as the basis for the market-leading thin-film solar-cell technology. With laboratory efficiencies approaching 20 per cent1, the research and development targets for CdTe are to reduce the cost of power generation further to less than half a US dollar per watt (ref. 2) and to minimize the environmental impact. A central part of the manufacturing process involves doping the polycrystalline thin-film CdTe with CdCl2. This acts to form the photovoltaic junction at the CdTe/CdS interface3, 4 and to passivate the grain boundaries5, making it essential in achieving high device efficiencies. However, although such doping has been almost ubiquitous since the development of this processing route over 25 years ago6, CdCl2 has two severe disadvantages; it is both expensive (about 30 cents per gram) and a water-soluble source of toxic cadmium ions, presenting a risk to both operators and the environment during manufacture. Here we demonstrate that solar cells prepared using MgCl2, which is non-toxic and costs less than a cent per gram, have efficiencies (around 13%) identical to those of a CdCl2-processed control group. They have similar hole densities in the active layer (9 × 1014 cm−3) and comparable impurity profiles for Cl and O, these elements being important p-type dopants for CdTe thin films. Contrary to expectation, CdCl2-processed and MgCl2-processed solar cells contain similar concentrations of Mg; this is because of Mg out-diffusion from the soda-lime glass substrates and is not disadvantageous to device performance. However, treatment with other low-cost chlorides such as NaCl, KCl and MnCl2 leads to the introduction of electrically active impurities that do compromise device performance. Our results demonstrate that CdCl2 may simply be replaced directly with MgCl2 in the existing fabrication process, thus both minimizing the environmental risk and reducing the cost of CdTe solar-cell production.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
A 2 hour fun and interactive workshop for students at the University of Liverpool that introduces the use of Microsoft Teams as a professional tool for collaborative working.
This document provides an overview of an interactive session on science and the read/write web for students. It introduces the inventor of the world wide web, Tim Berners-Lee, and his vision for a collaborative social web. It discusses the evolution of the web from a static read-only version 1.0 to the current more dynamic and social version 2.0. The session plan involves students using Slack for communication, Google Docs and Slides for collaborative creation of presentations on assigned topics, and SlideShare to publish their work to the wider web.
Optical spectroscopy techniques such as transmission, reflection, absorption, and photoluminescence measurements are important tools for characterizing the optical properties of semiconductor materials for photovoltaic applications. These techniques can determine the band gap type and energy, which are crucial for a material's suitability as a solar cell absorber. A direct band gap is preferable to an indirect band gap. Temperature-dependent absorption measurements provide insight into the temperature dependence of the band gap and allow comparison to density functional theory calculations. Characterizing defects through photoluminescence is also useful. Together, optical measurements provide essential information for understanding and improving photovoltaic materials.
This document discusses how solar cells work by using sunlight to create an electrical imbalance between n-type and p-type materials through the transfer of energy from photons to electrons, allowing the cells to generate electricity that can then be inverted for use.
The document discusses various solar cell technologies, including their world record efficiencies. It covers traditional silicon technologies, as well as thin-film technologies like CIGS and CdTe. Emerging technologies discussed include perovskites, dyes, organics, and multi-junction cells. For each technology, it provides the strengths and weaknesses, example efficiency levels, and sometimes a diagram. It aims to give an overview of both established and new concepts in photovoltaics.
1. The document discusses phase diagrams and thermodynamics of mixing.
2. It explains how phase diagrams can be used to determine the number and types of phases present, the composition of each phase, and the amount of each phase at a given temperature and composition.
3. Binary eutectic and eutectoid systems allow for a range of microstructures depending on the cooling rate, and alloying generally increases strength but decreases ductility due to solid solution strengthening.
An introduction to the fundamental physics of transparent conducting oxides including a review of the electrical and optical properties of common materials.
A Combinatorial Approach to the Optimisation of Cd (1−x) Zn x S Layers for Cd...University of Liverpool
A combinatorial methodology has been adopted to determine the optimum composition of a Cd ( 1 − x)Zn x S window
layer for CdTe solar cells. The methodology generated a large, self
consistent dataset which permitted an unambiguous relationship
between x, conversion efficiency and related cell parameters to
be determined. An optimum composition of x = 0.57 was shown
to maximise cell efficiency. Analysis of J − V curves, measured
over 72 separate cells show that both short circuit current, J SC ,
and fill factor, F F , values increase with respect to x over the
range 0.1−0.57. EQE measurements show that further increases
in J SC value are limited by the band gap of the highly resistive
transparent (HRT) ZnO layer. The methodology demonstrates a
rapid route, compared to conventional experiments, to the further
optimisation of CdTe solar cells.
A low-cost non-toxic post-growth activation step for CdTe solar cellsUniversity of Liverpool
Cadmium telluride, CdTe, is now firmly established as the basis for the market-leading thin-film solar-cell technology. With laboratory efficiencies approaching 20 per cent1, the research and development targets for CdTe are to reduce the cost of power generation further to less than half a US dollar per watt (ref. 2) and to minimize the environmental impact. A central part of the manufacturing process involves doping the polycrystalline thin-film CdTe with CdCl2. This acts to form the photovoltaic junction at the CdTe/CdS interface3, 4 and to passivate the grain boundaries5, making it essential in achieving high device efficiencies. However, although such doping has been almost ubiquitous since the development of this processing route over 25 years ago6, CdCl2 has two severe disadvantages; it is both expensive (about 30 cents per gram) and a water-soluble source of toxic cadmium ions, presenting a risk to both operators and the environment during manufacture. Here we demonstrate that solar cells prepared using MgCl2, which is non-toxic and costs less than a cent per gram, have efficiencies (around 13%) identical to those of a CdCl2-processed control group. They have similar hole densities in the active layer (9 × 1014 cm−3) and comparable impurity profiles for Cl and O, these elements being important p-type dopants for CdTe thin films. Contrary to expectation, CdCl2-processed and MgCl2-processed solar cells contain similar concentrations of Mg; this is because of Mg out-diffusion from the soda-lime glass substrates and is not disadvantageous to device performance. However, treatment with other low-cost chlorides such as NaCl, KCl and MnCl2 leads to the introduction of electrically active impurities that do compromise device performance. Our results demonstrate that CdCl2 may simply be replaced directly with MgCl2 in the existing fabrication process, thus both minimizing the environmental risk and reducing the cost of CdTe solar-cell production.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577