Tracy Schloemer

All Publications

• Triplet Fusion Upconversion Nanocapsule Synthesis. Journal of visualized experiments : JoVE Schloemer, T. H., Sanders, S. N., Zhou, Q., Narayanan, P., Hu, M., Gangishetty, M. K., Anderson, D., Seitz, M., Gallegos, A. O., Stokes, R. C., Congreve, D. N. 2022

  Abstract

  Triplet fusion upconversion (UC) allows for the generation of one high energy photon from two low energy input photons. This well-studied process has significant implications for producing high energy light beyond a material's surface. However, the deployment of UC materials has been stymied due to poor material solubility, high concentration requirements, and oxygen sensitivity, ultimately resulting in reduced light output. Toward this end, nanoencapsulation has been a popular motif to circumvent these challenges, but durability has remained elusive in organic solvents. Recently, a nanoencapsulation technique was engineered to tackle each of these challenges, whereupon an oleic acid nanodroplet containing upconversion materials was encapsulated with a silica shell. Ultimately, these nanocapsules (NCs) were durable enough to enable triplet fusion upconversion-facilitated volumetric three-dimensional (3D) printing. By encapsulating upconversion materials with silica and dispersing them in a 3D printing resin, photopatterning beyond the surface of the printing vat was made possible. Here, video protocols for the synthesis of upconversion NCs are presented for both small-scale and large-scale batches. The outlined protocols serve as a starting point for adapting this encapsulation scheme to multiple upconversion schemes for use in volumetric 3D printing applications.

  View details for DOI 10.3791/64374

  View details for PubMedID 36155426

• Triplet fusion upconversion nanocapsules for volumetric 3D printing. Nature Sanders, S. N., Schloemer, T. H., Gangishetty, M. K., Anderson, D., Seitz, M., Gallegos, A. O., Stokes, R. C., Congreve, D. N. 2022; 604 (7906): 474-478

  Abstract

  Three-dimensional (3D) printing has exploded in interest as new technologies have opened up a multitude of applications1-6, with stereolithography a particularly successful approach4,7-9. However, owing to the linear absorption of light, this technique requires photopolymerization to occur at the surface of the printing volume, imparting fundamental limitations on resin choice and shape gamut. One promising way to circumvent this interfacial paradigm is to move beyond linear processes, with many groups using two-photon absorption to print in a truly volumetric fashion3,7-9. Using two-photon absorption, many groups and companies have been able to create remarkable nanoscale structures4,5, but the laser powerrequired to drive this process has limited print size and speed, preventing widespread application beyond the nanoscale. Here we use triplet fusion upconversion10-13 to print volumetrically with less than 4milliwatt continuous-wave excitation. Upconversion is introduced to the resin by means of encapsulation with a silica shell and solubilizing ligands. We further introduce an excitonic strategy to systematically control the upconversion threshold to support either monovoxel or parallelized printing schemes, printing at power densities several orders of magnitude lower than the power densities required for two-photon-based 3D printing.

  View details for DOI 10.1038/s41586-022-04485-8

  View details for PubMedID 35444324

• Managing big data NATURE ENERGY Schloemer, T. H. 2022

  View details for DOI 10.1038/s41560-021-00972-w

  View details for Web of Science ID 000746760500001

• Reflections on hosting summer undergraduate researchers in the midst of a pandemic. Matter Gallegos, A. O., Ahmed, G. H., Schloemer, T. H., Congreve, D. N. 2021; 4 (10): 3074-3077

  Abstract

  The COVID-19 pandemic continues to impact nearly every aspect of our lives, including academic research. In this Matter of Opinion, we reflect on hosting both in-person and virtual undergraduate students during these challenging times.

  View details for DOI 10.1016/j.matt.2021.09.013

  View details for PubMedID 34632371

• The Molybdenum Oxide Interface Limits the High-Temperature Operational Stability of Unencapsulated Perovskite Solar Cells ACS ENERGY LETTERS Schloemer, T. H., Raiford, J. A., Gehan, T. S., Moot, T., Nanayakkara, S., Harvey, S. P., Bramante, R. C., Dunfield, S., Louks, A. E., Maughan, A. E., Bliss, L., McGehee, M. D., van Hest, M. M., Reese, M. O., Bent, S. F., Berry, J. J., Luther, J. M., Sellinger, A. 2020; 5 (7): 2349–60

  View details for DOI 10.1021/acsenergylett.0c01023

  View details for Web of Science ID 000552668000030

• CsI-Antisolvent Adduct Formation in All-Inorganic Metal Halide Perovskites ADVANCED ENERGY MATERIALS Moot, T., Marshall, A. R., Wheeler, L. M., Habisreutinger, S. N., Schloemer, T. H., Boyd, C. C., Dikova, D. R., Pach, G. F., Hazarika, A., McGehee, M. D., Snaith, H. J., Luther, J. M. 2020

  View details for DOI 10.1002/aenm.201903365

  View details for Web of Science ID 000510251700001

• Doping strategies for small molecule organic hole-transport materials: impacts on perovskite solar cell performance and stability. Chemical science Schloemer, T. H., Christians, J. A., Luther, J. M., Sellinger, A. 2019; 10 (7): 1904-1935

  Abstract

  Hybrid organic/inorganic perovskite solar cells (PSCs) have dramatically changed the landscape of the solar research community over the past decade, but >25 year stability is likely required if they are to make the same impact in commercial photovoltaics and power generation more broadly. While every layer of a PSC has been shown to impact its durability in power output, the hole-transport layer (HTL) is critical for several reasons: (1) it is in direct contact with the perovskite layer, (2) it often contains mobile ions, like Li+ - which in this case are hygroscopic, and (3) it usually has the lowest thermal stability of all layers in the stack. Therefore, HTL engineering is one method with a high return on investment for PSC stability and lifetime. Research has progressed in understanding design rules for small organic molecule hole-transport materials, yet, when implemented into devices, the same dopants, bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) and tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(iii) tri[bis(trifluoromethane)sulfonimide] (FK209), are nearly always required for improved charge-transport properties (e.g., increased hole mobility and conductivity). The dopants are notable because they too have been shown to negatively impact PSC stability and lifetime. In response, new research has targeted alternative dopants to bypass these negative effects and provide greater functionality. In this review, we focus on dopant fundamentals, alternative doping strategies for organic small molecule HTL in PSC, and imminent research needs with regard to dopant development for the realization of reliable, long-lasting electricity generation via PSCs.

  View details for DOI 10.1039/c8sc05284k

  View details for PubMedID 30881622

  View details for PubMedCentralID PMC6390699