Physics Commons^™

Carrier Mobility In Methylammonium Lead Iodide Perovskite Solar Cells: Mobility Versus Composition In Spin Coated And Vapor Deposited Samples, Max A. Zinman, James Heyman

Macalester Journal of Physics and Astronomy

We performed research on a set methylammonium lead iodide (MaPI) perovskite solar cell samples, including samples produced both by vapor deposition and spin coating. We used time resolved THz spectroscopy to measure carrier mobility in the samples and excitation of vibrational modes in the THz and IR spectra to gauge relative sample compositions (ratio of PbI to Ma). Plotting carrier mobilities against composition ratios, we found a peaked distribution of carrier mobilities suggesting an ideal ratio of lead iodide to methylammonium to maximize mobility. We also observed that the spin coated samples had considerably less variance in their composition ratios …

Solid Thermal Storage As An Energy Storage Device In Insulated Solar Electric Cookers: Thermal Modeling And Experiment, Michael Antonio Fernandez

Physics

The use of solid thermal storage (STS) as an energy storage device in insulated solar electric cookers (ISEC) was explored using a thermal simulation before retrofitting an existing cooker without energy storage and testing it under several conditions. STS sizing, material selection, and geometry were examined from both theoretical and practical perspectives and re-examined following experimental results. Characterization of the system’s thermal interfaces and methods to improve their thermal conductivities were investigated resulting in several performance enhancements to the system.

Determining The Phase Of The Diurnal, Solar Thermal Tidal Wave In The Upper Atmosphere Using Nighttime Na Lidar Measurements, Trevor Harshman

Physics Capstone Projects

Solar thermal tidal waves play a critical role in the dynamics of the mesosphere and thermosphere. Obtaining measurements of the diurnal tidal wave above 100 km is difficult. This could be solved using a physics-based empirical model. To derive this model requires knowing the phase at different points along the tidal wave. In this study, I determine the phase at multiple points along the thermal diurnal tidal wave using measurements taken by a fluorescence lidar in the range of 80 to 100 km. A simple calculation of the phase based on the zeroes and extrema of the wave is demonstrated.

An Investigation Of Diode Failure, Nicholas James Adams

Physics

Solar electricity can be used to cheaply cook food and charge electronic devices. We investigate the viability of using diodes as heating elements for insulated solar electric cooking (ISEC). In addition, information on designing and constructing ISEC compatible phone chargers and rechargeable LED lighting systems is included.

Dual-Axis Solar Tracker, Bryan Kennedy

All Undergraduate Projects

Renewable energies, and fuels that are not fossil fuel-based, are one of the prolific topics of debate in modern society. With climate change now becoming a primary focus for scientists and innovators of today, one of the areas for the largest amount of potential and growth is that of the capturing and utilization of Solar Energy. This method involves using a mechanical system to track the progression of the sun as it traverses the sky throughout the day. A dual-axis solar tracker such as the one designed and built for this project, can follow the sun both azimuthally and in …

Rocketry And Observability Predictions For Cubesat, Juliano A. Everett

Publications and Research

Estimating the visibility of Sunlight reflected by the holographic retro-reflector of Cubesat Alpha, and to convert this to star apparent magnitude to learn more about the visibility of these sails through reflected sunlight, to in turn determine if glints of these holograms are visible by terrestrial observers.

Application Of Silicon Nanohair Textured P-N Junctions In A Photovoltaic Device, Michael Small

Electronic Theses and Dissertations

The goal of this project is to design and develop a fabrication process for a silicon photovoltaic device which incorporates a nanohair textured p-n junction. The silicon nanowires are etched into a silicon wafer, comprising an epitaxial p-layer on n-substrate, via metal-assisted chemical etching (MACE). The resulting nanowires contain p-n junctions that lie along the length of the vertical nanowires. This construct has the potential to increase the optical bandwidth of a silicon photovoltaic device by allowing a greater amount of short wavelength light to reach the junction. In addition, the MACE method of nanofabrication has the potential for decreasing …

Solar Observatory: Shedding Light On The Surface Of The Sun, Zane F. Davis

Physics Capstone Projects

The Solar Observatory was used to observe the photosphere of the sun. The main focus to observer the photosphere are the sunspots and prominences that develop on the surface. These phenomenon can lead to Coronal Mass Ejections (CME’s). After taking pictures and analyzing them, there was only one day that had any activity on the photosphere. It was concluded that the sun is at it’s solar minima. This means that there is little to zero activity on the suns photosphere. With this, and more data over an extended period of time, it is possible to calculate a solar cycle.

Solar Powered Single-Axis Heliostat Active Solar Tracking Device, Mason Kyle Roberts

Physics

As a means of cooking food, the burning of biomass accounts for over 4 million premature deaths in third world countries (“Household Air Pollution and Health”). The focus of this project was to explore an alternative that could utilize focused sunlight to cook food. A solar tracker was designed to be affixed to a parabolic, reflective, tilted single axis heliostat to follow the sun throughout the day and focus the reflected light to the bottom of a cooking surface. This surface became hot enough to for the preparation of food or boiling/sterilization of water.

A goal for each project was …

Experimental Investigation Of Plasma Dynamics In Jets And Bubbles Using A Compact Coaxial Plasma Gun In A Background Magnetized Plasma, Yue Zhang

Electrical and Computer Engineering ETDs

Numerous solar and astrophysical observations of jet- and bubble-like plasma structures exhibit morphological similarities, suggesting that there may be common plasma physics at work in the formation and evolution processes of these structures at different system scales. The ideal magnetohydrodynamics (MHD) provide the necessary theoretical basis for employing laboratory experiments to investigate key physical processes in nonlinear astrophysical and solar systems, especially when magnetic fields are present.

A coaxial magnetized plasma gun has been designed, installed, and operated in the HelCat linear device at the University of New Mexico. In Region I, a current-driven plasma jet is formed. The plasma …

New Facet Of Solar Activities Revealed By High-Resolution Imaging At He I 10830 Å, Zhicheng Zeng

Dissertations

Major solar activities such as major flares and associated coronal mass ejections (CMEs), have a great impact on space weather, which requires us to develop the ability to predict them. Despite the extensive studies already made, however, many basic processes, such as energy accumulation processes in solar active regions and the triggering mechanism of solar activities, are still not well understood.

One reason why the basic processes are hard to be understood is that the large-scale activities are complicated, involving many small-scale energy releases, making it hard to understand the basic picture of the events. Small-scale solar activities, such as …

Electron And Hole Drift Mobility Measurements On Methylammonium Lead Iodide Perovskite Solar Cells, Brian Maynard, Qi Long, Eric A. Schiff, Mengjin Yang, Kai Zhu, Ranjith Kottokkaran, Hisham Abbas, Vikram L. Dalal

Physics - All Scholarship

We report nanosecond domain time-of-flight measurements of electron and hole photocarriers in methylammonium lead iodide perovskite solar cells. The mobilities ranged from 0.06 to 1.4 cm2/Vs at room temperature, but there is little systematic difference between the two carriers. We also find that the drift mobilities are dispersive (time-dependent). The dispersion parameters are in the range of 0.4–0.7, and they imply that terahertz domain mobilities will be much larger than nanosecond domain mobilities. The temperature-dependences of the dispersion parameters are consistent with confinement of electron and hole transport to fractal-like spatial networks within nanoseconds of their photogeneration.

Analyzing Major Challenges Of Wind And Solar Variability In Power Systems, Falko Ueckerdt, Robert Brecha, Gunnar Luderer

Robert J. Brecha

Ambitious policy targets together with current and projected high growth rates indicate that future power systems will likely show substantially increased generation from renewable energy sources. A large share will come from the variable renewable energy (VRE) sources wind and solar photovoltaics (PV); however, integrating wind and solar causes challenges for existing power systems. In this paper we analyze three major integration challenges related to the structural matching of demand with the supply of wind and solar power: low capacity credit, reduced utilization of dispatchable plants, and over-produced generation. Based on residual load duration curves we define corresponding challenge variables …

Photovoltaics: An Investigation Into The Origins Of Efficiency On All Scales, Jeremy Alexander Bannister

Senior Projects Spring 2016

This project is comprised of a set of parallel investigations, which share the common mo- tivation of increasing the efficiency of photovoltaics. First, the reader is introduced to core concepts of photovoltaic energy conversion via a semi-classical description of the phys- ical system. Second, a key player in photovoltaic efficiency calculations, the exciton, is discussed in greater quantum mechanical detail. The reader will be taken through a nu- merical derivation of the low-energy exciton states in various geometries, including a line segment, a circle and a sphere. These numerical calculations are done using Mathematica, a computer program which, due to …

Analyzing Major Challenges Of Wind And Solar Variability In Power Systems, Falko Ueckerdt, Robert Brecha, Gunnar Luderer

Physics Faculty Publications

Ambitious policy targets together with current and projected high growth rates indicate that future power systems will likely show substantially increased generation from renewable energy sources. A large share will come from the variable renewable energy (VRE) sources wind and solar photovoltaics (PV); however, integrating wind and solar causes challenges for existing power systems. In this paper we analyze three major integration challenges related to the structural matching of demand with the supply of wind and solar power: low capacity credit, reduced utilization of dispatchable plants, and over-produced generation. Based on residual load duration curves we define corresponding challenge variables …

Analysis And Optimization Of The Scheffler Solar Concentrator, Simone Alberti

Master's Theses

The Scheffler reflector is a new solar concentrator design which maintains a fixed focus while only having a single axis tracking mechanism. This design makes the construction and operation of high temperature solar concentrators accessible to developing nations. In this project, I wrote computer simulation codes to better understand the dynamics and the effect of deformation or deviations from ideal conditions in order to define necessary manufacturing and operational tolerances. These tools and knowledge drove the prototyping of new reflector concepts by myself and other students on my team. A fiberglass prototype was able to drive the cost of a …

Carbon Nitride And Conjugated Polymer Composite Materials, Josh Byers

Electronic Thesis and Dissertation Repository

The semiconductor and photovoltaic properties of carbon nitride (CNx) thin films prepared using a reactive magnetron sputtering technique were investigated both individually and as composites with the organic conjugated polymers polybithiophene (PBT) and poly(3-hextlthiophene) (P3HT). At low nitrogen content, the film structure was dominated by graphitic sp² percolation networks, whereas at higher nitrogen contents CNx films started to demonstrate semiconductor properties, as evidenced by the occurrence of photoconductivity and the development of a space charge region. When CNx was deposited onto a PBT substrate, it was found to function as an acceptor material improving the photocurrent generation both in …

An Investigation Into Dual-Axis Solar Tracking, Daniel Spaizman

Physics

This senior project aims to determine a) if using a controlled photon-tracking system does produce greater voltage output than a fixed panel and b) by how much, if so. To do this, I built a dual-axis solar tracker using a small solar panel, some stepper motors, and an Arduino Uno. The majority of my time was spent familiarizing myself with the electrical components and fabricating the device. To test the performance of the panel, the leads of the solar panel were attached to the Arduino to record the output voltages. Two experiments were carried out to discover the answers to …

Lamination Of Inverted Organic Photovoltaics And Associated Physical Properties, Brian A. Bailey

Electronic Theses and Dissertations

This dissertation is the result of a series of studies involving hot press lamination of inverted organic photovoltaics. It first gives background and develops a lamination process for fabrication. Then, the process is used to answer fundamental questions about organic photovoltaics and to fabricate previously impossible or overly complicated devices. Finally, the author examines the scientific theory which describes the process and aligns that theory with related measurements.

The field of organic photovoltaics is introduced and the lamination process is developed and optimized. In the lamination process, part of the solar cell is deposited onto a rigid substrate, and the …

Multipolymer Interactions In Bulk Heterojunction Photovoltaic Devices, Grant Olson

Physics

Multipolymer photovoltaics, single layer devices made up of multiple photoactive polymers, can create organic photovoltaics (OPVs) with a wider spectral response than single polymer systems without the difficult fabrication of a tandem. Our group has successfully created multipolymer solar devices with 2% power conversion efficiency. We have analyzed the optical and electrical properties of these devices, and found that it may be possible for polymers to assist each other with charge extraction, though combining polymers disrupts single polymer crystallinity.

Observations Of The Vertical Ion Drift In The Equatorial Ionosphere During The Solar Minimum Period Of 2009, R. A. Stoneback, R. A. Heelis, A. G. Burrell, W. R. Coley, Bela G. Fejer, E. Pacheco

Bela G. Fejer

[1] The extended solar minimum conditions in 2008 and 2009 presented an opportunity to investigate the ionosphere at lower solar activity levels than previously observed. The Coupled Ion Neutral Dynamics Investigation (CINDI) Ion Velocity Meter (IVM) instrument onboard the Communication/Navigation Outage Forecasting System is used to construct the median meridional (vertical) ion drifts, ion densities, and O+ concentrations during periods of low geomagnetic activity for four characteristic seasons each year spanning late 2008 to 2010. The presence of a large semidiurnal component in the ion drift variation at the equator produced significant differences from typical ionospheric conditions. Instead of upward …

Spatial Light Dilution As A Technique For Conversion Of Solar Energy To Algal Biomass, Daniel J. Dye

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A photobioreactor has been designed and developed to efficiently utilize solar irradiance through spatial dilution of sunlight. The concept of spatial light dilution is simple: incident sunlight is spread over a large surface area, thus reducing the photon flux density of the light. The implementation of this technique, however, is difficult. The reactor described within uses a new approach to spatial light dilution, utilizing recently-developed optical components to diffuse concentrated sunlight inside an algae culture. Preliminary productivity tests indicate a 2-3 fold increase in productivity per unit aperture (sunlight collection area) over a control reactor with direct-sunlight. Aperture productivity of …

Construction And Improvement Of A Scheffler Reflector And Thermal Storage Device, Jason Rapp

Physics

We constructed and successfully tested a 2 m2 parabolic dish solar concentrator (Scheffler Concentrator) to focus sunlight onto a stationary target. Present efforts are to decrease the construction complexity and cost of the concentrator. In order to store solar heat, we also constructed and are testing a thermal storage device made of sand (for thermal mass), and pumice (for insulation). Preliminary tests indicate thermal retention times of many hours. Present efforts are to increase accessible power, and structural integrity.

Luminescent Solar Concentrators: A Review Of Recent Results, Wilfrid G.J.H.M. Van Sark, Keith W.J. Barnham, Lenneke H. Slooff, Amanda J. Chatten, Andreas Buchtemann, Andreas Meyer, Sarah Mccormack, Rolf Koole, Daniel J. Farrell, Rahul Bose, Evert E. Bende, Antonius R. Burgers, Tristram Budel, Jana Quilitz, Manus Kennedy, Toby Meyer, C. De Mello Donega, Andries Meijerink

Articles

Luminescent solar concentrators (LSCs) generally consist of transparent polymer sheets doped with luminescent species. Incident sunlight is absorbed by the luminescent species and emitted with high quantum efficiency, such that emitted light is trapped in the sheet and travels to the edges where it can be collected by solar cells. LSCs offer potentially lower cost per Wp. This paper reviews results mainly obtained within the framework of the Fullspectrum project. Two modeling approaches are presented, i.e., a thermodynamic and a ray-trace one, as well as experimental results, with a focus on LSC stability.

Design And Application Of Near Infrared Tunable Filter For Atst And Nst, Jun Ma

Dissertations

This thesis includes the following sections: a general design of the Near Infrared Tunable Filter (NIRTF) of Advanced Technology Solar Telescope (ATST) project and the Near Infrared Imaging Magnetograph (IRIM) of the New Solar Telescope (NST), the design of achromatic waveplates, the narrowband continuum observation of a Sunspot at 1.56 µm using IRIM instruments, and the coronal hole observation using the Digital Vector Magnetograph (VMG) at Big Bear Solar Observatory (BBSO).

A near infrared tunable filter system is designed with detailed optical parameters for each component in the system. Among these components, the achromatic waveplates, which used to be an …

High Resolution Solar Observations In The Context Of Space Weather Prediction, Guo Yang

Dissertations

Space weather has a great impact on the Earth and human life. It is important to study and monitor active regions on the solar surface and ultimately to predict space weather based on the Sun's activity. In this study, a system that uses the full power of speckle masking imaging by parallel processing to obtain high-spatial resolution images of the solar surface in near real-time has been developed and built. The application of this system greatly improves the ability to monitor the evolution of solar active regions and to predict the adverse effects of space weather. The data obtained by …

Longitudinal Ionosphericeffects In The South Atlantic Sector During Solar Maximum, E. R. De Paula, J. R. Souza, Bela G. Fejer, G. J. Bailey, R. A. Heelis

Bela G. Fejer

[1] Large-scale horizontal gradients in ion density and vertical drift observed by the Atmospheric Explorer E satellite in the South Atlantic region (latitudes 10°S–20°S, longitudes 50°W–10°E) during the June solstice at solar maximum are presented and analyzed. These features occur during the nighttime period. The observations near 450-km altitude show vertically downward ion drift velocities exceeding 120 m s−1 and depleted regions where the ion density is around 2 × 104 cm−3. It is shown, using values modeled by the Sheffield University Plasmasphere Ionosphere Model (SUPIM) along the satellite trajectory, that the large ion density depletions appear as a result …

Equatorial And Low Latitude Thermospheric Winds: Measured Quiet Time Variations With Season And Solar Flux From 1980 To 1990, M. A. Biondi, S. Y. Sazykin, Bela G. Fejer, J. W. Meriwether, C. G. Fesen

Bela G. Fejer

Thermospheric winds have been systematically determined at Arequipa, Peru, and Arecibo, Puerto Rico, from Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630 nm line. The wind databases (1983 – 1990 at Arequipa and 1980 – 1990 at Arecibo) have been edited to eliminate measurements during geomagnetically disturbed conditions, then sorted by season and solar flux level. Following this, they were averaged to obtain the climatological behavior of the nighttime wind variations at the two locations. A new averaging technique, multivariate regression analysis, has been applied to the data, and the results compared to our prior binning averages. The …

Solar Cycle And Seasonal Variationsin F Region Electrodynamics At Millstone Hill, M. J. Buonsanto, M. E. Hagan, J. E. Salah, Bela G. Fejer

Bela G. Fejer

Incoherent scatter radar observations of ion drifts taken at Millstone Hill (42.6°N, 288.5°E) during 73 experiments in the period February 1984 to February 1992 are used to construct, for the first time at this station, average quiet-time E×B drift patterns for both solar cycle maximum and minimum, for the summer, winter, and equinox seasons. The daily variation of V⊥N shows a reversal from northward to southward drifts near noon, and a return to northward drifts in the premidnight hours. The weaker southward drift in the afternoon in summer noted by Wand and Evans (1981) is shown to occur only at …

F-Region Plasma Drifts Over Arecibo: Solar Cycle, Seasonal And Magnetic Activityeffects, Bela G. Fejer

Bela G. Fejer

We have used Arecibo incoherent scatter measurements from 1981 to 1990 to determine the characteristics of low-latitude F region plasma drifts. The measurements show large day-to-day variability even during magnetically quiet periods. The average poleward/perpendicular plasma drifts do not change significantly with season and solar cycle except in the midnight-morning sector. The zonal drifts show clear solar cycle and seasonal effects. The afternoon-nighttime eastward drifts increase with solar flux; the westward drifts in the early morning-afternoon sector show a large increase from summer to winter but are independent of solar activity. The two perpendicular velocity components also respond differently to …