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Your search keyword '"Tumbleston, John R."' showing total 133 results
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133 results on '"Tumbleston, John R."'

1. Results of an interlaboratory study on the working curve in vat photopolymerization

Author

Kolibaba, Thomas J., Killgore, Jason P., Caplins, Benjamin W., Higgins, Callie I., Arp, Uwe, Miller, C. Cameron, Poster, Dianne L., Zong, Yuqin, Broce, Scott, Wang, Tong, Talačka, Vaidas, Andersson, Jonathan, Davenport, Amelia, Panzer, Matthew A., Tumbleston, John R., Gonzalez, Jasmine M., Huffstetler, Jesse, Lund, Benjamin R., Billerbeck, Kai, Clay, Anthony M., Fratarcangeli, Marcus R., Qi, H. Jerry, Porcincula, Dominique H., Bezek, Lindsey B., Kikuta, Kenji, Pearlson, Matthew N., Walker, David A., Long, Corey J., Hasa, Erion, Aguirre-Soto, Alan, Celis-Guzman, Angel, Backman, Daniel E., Sridhar, Raghuveer Lalitha, Cavicchi, Kevin A., Viereckl, RJ, Tong, Elliott, Hansen, Christopher J., Shah, Darshil M., Kinane, Cecelia, Pena-Francesch, Abdon, Antonini, Carlo, Chaudhary, Rajat, Muraca, Gabriele, Bensouda, Yousra, Zhang, Yue, and Zhao, Xiayun

Published
2024
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2. Growing three-dimensional objects with light.

Author

Lipkowitz, Gabriel, Saccone, Max A., Panzer, Matthew A., Coates, Ian A., Kaiwen Hsiao, Ilyn, Daniel, Kronenfeld, Jason M., Tumbleston, John R., Shaqfeh, Eric S. G., and DeSimone, Joseph M.

Subjects
OPTICAL coherence tomography, FABRICATION (Manufacturing), PHOTOPOLYMERIZATION
Abstract

Vat photopolymerization (VP) additive manufacturing enables fabrication of complex 3D objects by using light to selectively cure a liquid resin. Developed in the 1980s, this technique initially had few practical applications due to limitations in print speed and final part material properties. In the four decades since the inception of VP, the field has matured substantially due to simultaneous advances in light delivery, interface design, and materials chemistry. Today, VP materials are used in a variety of practical applications and are produced at industrial scale. In this perspective, we trace the developments that enabled this printing revolution by focusing on the enabling themes of light, interfaces, and materials. We focus on these fundamentals as they relate to continuous liquid interface production (CLIP), but provide context for the broader VP field. We identify the fundamental physics of the printing process and the key breakthroughs that have enabled faster and higher-resolution printing, as well as production of better materials. We show examples of how in situ print process monitoring methods such as optical coherence tomography can drastically improve our understanding of the print process. Finally, we highlight areas of recent development such as multimaterial printing and inorganic material printing that represent the next frontiers in VP methods. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Continuous liquid interface production of 3D objects

Author

Tumbleston, John R., Shirvanyants, David, Ermoshkin, Nikita, Janusziewicz, Rima, Johnson, Ashley R., Kelly, David, Chen, Kai, Pinschmidt, Robert, Rolland, Jason P., Ermoshkin, Alexander, Samulski, Edward T., and DeSimone, Joseph M.

Published
2015

10. Nonideal parasitic resistance effects in bulk heterojunction organic solar cells

Author

Tumbleston, John R., Doo-Hyun Ko, Samulski, Edward T., and Lopez, Rene

Subjects
Solar batteries -- Analysis, Solar cells -- Analysis, Absorption of light -- Analysis, Physics
Abstract

The relaxation of the assumption that series resistance is near zero while shunt resistance approaches infinity has affected the device performance differently depending on the chosen bulk heterojunction (BHJ) material system. The equivalent circuit model has used a light intensity dependent shunt resistance to describe the dissociation process and has predicted a photocurrent under reverse bias that has exceeded the photocurrent permitted by light absorption.

Published
2010

11. Suppression of bimolecular recombination by UV-sensitive electron transport layers in organic solar cells

Author

Doo-Hyun Ko, Tumbleston, John R., Myoung-Ryul Ok, Honggu Chun, Lopez, Rene, and Samulski, Edward

Subjects
Solar batteries -- Analysis, Solar cells -- Analysis, Physics
Abstract

Incorporating UV-sensitive electron transport layers (ETLs) into organic bulk heterojunction (BHJ) photovoltaic devices has affected short-circuit current ([J.sub.SC]) and fill factor characteristics. Electro-optical modeling and light intensity experiments have shown that bimolecular recombination, in the form of diode current losses, has controlled the extracted photocurrent and is dependently on the ETL resistivity.

Published
2010

16. Photonics and transport in bulk heterojunction organic solar cells

Author

Tumbleston, John R.

Abstract

In this thesis, the groundwork is established for a new type of bulk heterojunction (BHJ) organic solar cell geometry that has photonic crystal (PC) photoactive layers. This design is motivated by the need to improve light absorption without increasing active layer thickness, which for many BHJ systems, degrades electrical performance. It is demonstrated that with the right choice of materials and cell dimensions, quasiguided or resonant modes are excited near the band edge of a variety of BHJ blends to enhance absorption. Resonant modes are predicted by first developing a scattering matrix optical model and then observed in wavelength-, polarization-, and angular-dependent reflection and photocurrent measurements. PC cells are fabricated using a facile nanopatterning technique, where highly ordered arrays of submicron features are constructed over large areas in a single step. Optical and electrical function of this new cell architecture is fully explored in this thesis. Through optical measurements and modeling, PC devices show clear enhancements in light absorption. On the other hand, the impact of the nonplanar geometry on electrical performance is not as easily deduced due to the multitude of electrical processes that lead to photocurrent generation. First, the electrical properties of the electron transporting layer that interfaces with the BHJ nanopattern and provides optical contrast in the PC greatly affect parasitic resistances in the solar cell. By including resistance losses in a drift/diffusion numerical model that describes electrical performance, it is shown that these losses greatly influence fundamental steps leading to photocurrent generation. This is confirmed with experiment by comparing two BHJ material systems that have different affinities for exciton separation. Second, significant levels of free carrier recombination are predicted by the electro-optical model due to the relatively long transport paths in the nanopattern features. To test this prediction, an experimental technique is developed to measure the transport lengths of photogenerated electrons and holes in BHJ solar cells. It is found that transport lengths of positive and negative carriers are mismatched and helps explain both PC electrical performance and recent conflicting results of planar BHJ solar cells in the literature.

Published
2011
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32. On the role of intermixed phases in organic photovoltaic blends

Author

Westacott, Paul, primary, Tumbleston, John R., additional, Shoaee, Safa, additional, Fearn, Sarah, additional, Bannock, James H., additional, Gilchrist, James B., additional, Heutz, Sandrine, additional, deMello, John, additional, Heeney, Martin, additional, Ade, Harald, additional, Durrant, James, additional, McPhail, David S., additional, and Stingelin, Natalie, additional

Published
2013
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36. The Importance of Fullerene Percolation in the Mixed Regions of Polymer–Fullerene Bulk Heterojunction Solar Cells

Author

Bartelt, Jonathan A., primary, Beiley, Zach M., additional, Hoke, Eric T., additional, Mateker, William R., additional, Douglas, Jessica D., additional, Collins, Brian A., additional, Tumbleston, John R., additional, Graham, Kenneth R., additional, Amassian, Aram, additional, Ade, Harald, additional, Fréchet, Jean M. J., additional, Toney, Michael F., additional, and McGehee, Michael D., additional

Published
2012
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