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Your search keyword '"Erika Colin Ulloa"' showing total 11 results
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11 results on '"Erika Colin Ulloa"'

1. Effects of polyethylene oxide particles on the photo-physical properties and stability of FA-rich perovskite solar cells

Author

Richard K. Koech, Yusuf A. Olanrewaju, Reisya Ichwani, Moses Kigozi, Deborah O. Oyewole, Omolara V. Oyelade, Dahiru M. Sanni, Sharafadeen A. Adeniji, Erika Colin-Ulloa, Lyubov V. Titova, Julia L. Martin, Ronald L. Grimm, Abdulhakeem Bello, Oluwaseun K. Oyewole, Esidor Ntsoenzok, and Winston O. Soboyejo

Subjects
Medicine, Science
Abstract

Abstract In this paper, we use Polyethylene Oxide (PEO) particles to control the morphology of Formamidinium (FA)-rich perovskite films and achieve large grains with improved optoelectronic properties. Consequently, a planar perovskite solar cell (PSC) is fabricated with additions of 5 wt% of PEO, and the highest PCE of 18.03% was obtained. This solar cell is also shown to retain up to 80% of its initial PCE after about 140 h of storage under the ambient conditions (average relative humidity of 62.5 ± 3.25%) in an unencapsulated state. Furthermore, the steady-state PCE of the PEO-modified PSC device remained stable for long (over 2500 s) under continuous illumination. This addition of PEO particles is shown to enable the tuning of the optoelectronic properties of perovskite films, improvements in the overall photophysical properties of PSCs, and an increase in resistance to the degradation of PSCs.

Published
2022
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3. Bottom-up, scalable synthesis of anatase nanofilament-based two-dimensional titanium carbo-oxide flakes

Author

Hussein O. Badr, Tarek El-Melegy, Michael Carey, Varun Natu, Mary Q. Hassig, Craig Johnson, Qian Qian, Christopher Y. Li, Kateryna Kushnir, Erika Colin-Ulloa, Lyubov V. Titova, Julia L. Martin, Ronald L. Grimm, Rahul Pai, Vibha Kalra, Avishek Karmakar, Anthony Ruffino, Stefan Masiuk, Kun Liang, Michael Naguib, Olivia Wilson, Andrew Magenau, Kiana Montazeri, Yucheng Zhu, Hao Cheng, Takeshi Torita, Masashi Koyanagi, Akimaro Yanagimachi, Thierry Ouisse, Maxime Barbier, Fabrice Wilhelm, Andrei Rogalev, Jonas Björk, Per O.Å. Persson, Johanna Rosen, Yong-Jie Hu, and Michel W. Barsoum

Subjects
Mechanics of Materials, Mechanical Engineering, General Materials Science, Condensed Matter Physics
Published
2022
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9. Scalable, inexpensive, one-pot, facile synthesis of crystalline two-dimensional birnessite flakes

Author

Hussein O. Badr, Kiana Montazeri, Tarek El-Melegy, Varun Natu, Michael Carey, Ramchandra Gawas, Phu Phan, Qian Qian, Christopher Y. Li, Ulf Wiedwald, Michael Farle, Erika Colin-Ulloa, Lyubov V. Titova, Marc Currie, Thierry Ouisse, Maxime Barbier, Andrei Rogalev, Fabrice Wilhelm, Marcus Hans, Jochen M. Schneider, Christopher Tandoc, Young-Jie Hu, Joshua Snyder, and Michel W. Barsoum

Subjects
General Materials Science, Physik (inkl. Astronomie)
Published
2022

10. Pressure-Induced Void and Crack Closure Improves the Photoconversion Efficiency and Stability of Perovskite Solar Cells

Author

R. K. Koech, S. A. Adeniji, O. K. Oyewole, Lyubov V. Titova, Reisya Ichwani, Jaya Cromwell, Benjamin Agyei-Tuffour, Erika Colin Ulloa, Omolara Oyelade, Nancy A. Burnham, D. O. Oyewole, Juan Hinostroza Tamayo, Winston O. Soboyejo, and Ridwan Ahmed

Subjects
Crack closure, Materials science, Void (composites), Composite material, Stability (probability), Perovskite (structure)
Abstract

One route to a brighter global energy future may be through enhancing the efficiency and stability of perovskite solar cells (PSCs), which depends on the level of defects in the photoactive absorber and along the interfaces of the multilayered structure. Here, we use a combined experimental and theoretical approach to study the effects of pressure-induced compaction of microvoids and closure of cracks on the power conversion efficiency (PCEs) and stability of formamidinium-rich PSCs. A range of mechanical pressures was applied to the PSCs to reduce pre-existing grain-boundary voids and interfacial cracks within the devices. The PCEs of the PSCs increased from ~19.5% to ~ 23.5% for applied pressures between ~ (0 – 7) MPa. Unlaminated device stability increased by 33%, falling to 80% of initial PCE in 1800 hrs without compression, as compared to 2400 hrs with compression. The implications of this study are discussed in light of possible future manufacturing processes.

Published
2020
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11. From Graphene Oxide to Graphene: Tuning THz Properties by Reduction and Metal Intercalation

Author

Teng Shi, Sanjay Karna, Kateryna Kushnir, Lyubov V. Titova, Erika Colin Ulloa, and Joshua R. Uzarski

Subjects
010302 applied physics, Materials science, Terahertz radiation, business.industry, Graphene, Attenuation, Intercalation (chemistry), Oxide, 02 engineering and technology, Conductivity, 021001 nanoscience & nanotechnology, 01 natural sciences, Electromagnetic interference, law.invention, Metal, chemistry.chemical_compound, chemistry, law, visual_art, 0103 physical sciences, visual_art.visual_art_medium, Optoelectronics, 0210 nano-technology, business
Abstract

We investigate properties of reduced graphene oxide films in the THz frequency range. We demonstrate tuning their conductivity and THz attenuation by reduction as well as by intercalation of metals. These findings suggest that graphene oxide holds promise for electromagnetic interference shielding and other THz device applications.

Published
2020
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