Matching Items (374)
Description
Cadmium Telluride (CdTe) is a promising II–VI photovoltaic material, offering a detailed-balance efficiency limit around 30%. However, achieving this potential in practice requires minimizing non-radiative losses. This thesis examines the effects of black-body radiation of a CdTe/InSb solar cell absorber layer. Here, both experimental and theoretical approaches are used to understand how black-body emission and recombination losses influence solar cell device performance. Key topics include black-body radiation fundamentals, calibration of a black-body source, optical absorption in monocrystalline vs. polycrystalline CdTe absorbers, the Shockley–Queisser limit under radiative recombination, and photoluminescence quantum efficiency (PLQE) measurements. The goal was to understand how intrinsic thermal radiation and device design limit open-circuit voltage and efficiency, and how advanced structural engineering such as heterostructure barrier layers can mitigate these limits. In fact, the PLQE of the measured sample appeared to be extremely low: 6×10^(-7)%, which indicated a very large non-radiative recombination. Transmission Electron Microscopy and Solar Cell Modelling were utilized to explain this result. By using modified Shockley–Queisser approach to account for large non-radiative recombination, a more realistic maximum efficiency of 9.28% was calculated.
ContributorsVoinkov, Ky (Author) / Zhang, Yong-Hang (Thesis director) / Smith, David (Committee member) / Ju, Zheng (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor) / Department of Physics (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2025-05
Description
Structural color is the phenomenon where features of the material’s structure interact with light, causing it to interfere with itself, producing color. Examples of structural color are seen everywhere from the rainbow pattern on the back of CDs to the color of a butterfly's wings. Optical thin films that make use of structural color are used in a massive range of industries however, a typical thin film stack is limited to the configuration it is set in upon fabrication, thus tunable devices able to change their configuration would have huge potential for use in multi-functional devices to fill the gap of tunable optical thin film technology. A Floating Solid-State Thin Film (FSTF), where an applied voltage moves a metal film through a dielectric one, producing structure changes which change the device’s color, is one such device and Polymer-assisted Photochemical Deposition is a technique able to 3D print metal thin films of the same element used in prior FSTF research in a desired pattern without vacuum or heating. PPD could greatly improve the efficiency of micro- and opto-electronics manufacturing and the author’s group has previously done work comparing optical thin film structures made with PPD films to those made with conventionally deposited metals and they have shown promising results in this space. The purpose of this project then was to investigate whether a PPD metal film was capable of the migration demonstrated by a conventional film to function in a FSTF device. Devices of several architectures with SiO or PMMA dielectric layers and thermally evaporated or PPD silver metal layers were fabricated using a variety of techniques. The devices were tested by being connected to a 1 V and 4.5 V battery with the voltage applied being measured during testing and the device behaviors were observed. Blindspots and possible points of weakness in the experimental plan were identified post testing in both device testing and device design. These included unaccountability of the testing set-up for voltage drops creating uncertainty in the actual voltage needed and the actual voltage applied to the film as well as metal thin film thickness preventing device function in some cases by reflecting light away from the device cavity. Improvements which address these issues were identified and a new device design as well as improvements to the testing set-up were described which could be used in future work.
ContributorsBorea, Dante (Author) / Wang, Chao (Thesis director) / Yao, Yu (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor) / School for Engineering of Matter,Transport & Enrgy (Contributor)
Created2025-05
Description
Due to the natural abundance of sodium in the Earth’s crust and its low specific cost, new research has shown that Sodium Ion Batteries (SIBs) are an increasingly viable solution for sustainable energy storage. SIBs have the potential to be a more cost-effective alternative to Li-Ion batteries. However, there are several performance issues that hinder their charge capacity and capacity retention, largely attributed to electrode-electrolyte side reactions. In order to be effectively commercialized, these issues must be investigated, understood, and improved upon. It has been observed that the electrode-electrolyte interface (EEI) has a large impact on the overall cell performance in SIBs. While EEI layers are still trying to be fully understood, there is evidence that suggests electrolyte additives may assist the formation of synergistic EEI layers that can improve these major capacity issues in SIBs. Here, the use of three electrolyte additives (FEC, TMSB, and VC) with the MuNC cathode material is reported. From electrochemical cycling data, it was found that these additives greatly extend the lifetime of the MuNC cathode material. Further analysis is performed to understand the effectiveness of electrolyte additives as a solution to stability issues in Na-ion batteries.
ContributorsJacobs, Matthew (Author) / Mu, Linqin (Thesis director) / Chan, Candace (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor)
Created2025-05
Description
The misuse of personal pronouns when referring to individuals has increased immensely, and as a result, misgendering has become commonplace. This creates uncomfortable social situations and can exacerbate already stressful situations such as meeting new people or traveling to new places. Taking information from my own experiences with these issues when abroad and combining with personal experiences from other individuals, the added stress due to misgendering can be addressed effectively. Data collection occurred in order to address awareness of situations, inclusivity of locations, and language when referring to people. A survey was used as a medium to gather the data. Questions asked related to the relationship between inclusivity and misgendering as well as unfamiliarity and travel. Information gathered in this study yielded two major takeaways: misgendering occurs similarly between individuals familiar and unfamiliar with the knowledge of gender-inclusivity and misgendering, and that further awareness of misgendering should be brought to the public. Further suggestions were created to better address the conclusions. The simplest action is to ask for an individual’s personal pronouns or gender identity when meeting them for the first time. This eliminates the chance of misgendering by unfamiliarity by making the other party familiar with the gender identity. The second suggestion is to use more words that do not address one gender in particular.
ContributorsGlaser, Sam (Author) / Briggs, Georgette (Thesis director) / Thomas, Kathy (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05