Alexander Uhl

Assistant Professor

Mechanical
Office: EME4229
Phone: 250-807-8930
Email: alexander.uhl@ubc.ca

Graduate student supervisor



Research Summary

Solar energy conversion; Photovoltaics; Solar fuels; Thin film semiconductors

Courses & Teaching

Materials Selection and Design, Alternative Energy Systems, Solar Cell Engineering

Biography

Alexander R. Uhl received his PhD in Materials Science and Engineering from the Swiss Federal Institute of Technology in Zurich (ETH), Switzerland and Diploma in Nanoscale Engineering from the University of Würzburg, Germany after graduate stays at the University of British Columbia, Canada and Uppsala University, Sweden.  As a three-time fellow of the Swiss National Science Foundation (SNSF), he conducted postdoctoral research at the University of Washington, USA with Prof. Hugh Hillhouse and at the Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland with Prof. Michael Graetzel and Prof. Anders Hagfeldt.

Dr. Uhl joined the Okanagan School of Engineering at the University of British Columbia in January 2019. With a focus on materials and technologies for solar energy conversion, Dr. Uhl develops printed solar cells, tandem devices, and photoelectrochemical devices for clean and renewable electricity and storable fuels. His devices currently hold the world record for the highest power conversion efficiency for Culn(S,Se)2 solar cells from any non-vacuum process. Dr. Uhl has filed two patents on solution-processed chalcogenide solar cells, is the author of an invited book chapter on perovskite solar cells, and acts as guest editor for the scientific journal Thin Solid Films.

Websites

Laboratory for Solar Energy and Fuels (LSEF) Research Website

Degrees

Research Associate – Chemical Engineering – EPFL, Switzerland
Postdoctoral Fellow – Chemical Engineering – University of Washington, United States
PhD – Materials Science & Engineering – ETH Zurich, Switzerland
Diploma – Nanoscale Engineering – University of Wuerzburg, Germany

Research Interests & Projects

Solution-processed thin film solar cells

Ink-based deposition techniques, such as ink-jet printing, spray-, or slot-die coating, have the potential to bring down costs and allow sustainable growth of renewable technologies due to their low capital expenditure, high material utilization, and high throughput, if high device efficiencies and benign reaction mechanisms can be obtained at the same time. Thin film solar cells based on chalcogenide and perovskite absorbers are particularly promising as they have achieved power conversion efficiencies of over 22%, representing the highest value among thin film solar cells – exceeding market-leading multicrystalline Si – and can be fabricated by liquid deposition methods and on a choice of rigid or flexible substrates.

Selected publications:

  1. A. R. Uhl, J. K. Katahara, and H. W. Hillhouse, Molecular-ink route to 13.0% efficient low-bandgap CuIn(S,Se)2 and 14.7% efficient Cu(In,Ga)(S,Se)2 solar cellsEnergy & Environmental Science, 2016, vol. 9, pp. 130-134. (link)
  2. H. Xin, S. M. Vorpahl, A. D. Collord, I. L. Braly, A. R. Uhl, B. W. Krueger, D. S. Ginger, and H. W. Hillhouse, Lithium-Doping Affects the Nanoscale Electrical Properties of Grains and Grain Boundaries of Cu2ZnSn(S,Se)4Physical Chemistry Chemical Physics, 2015, vol. 17, pp. 23859-23866. (link)
  3. A. Chirila, P. Reinhard, F. Pianezzi, P. Bloesch, A. R. Uhl, C. Fella, L. Kranz, D. Keller, C. Gretener, H. Hagendorfer, D. Jaeger, R. Erni, S. Nishiwaki, S. Buecheler, and A. N. Tiwari, Potassium-induced surface modification of Cu(In,Ga)Se2 thin films for high-efficiency solar cellsNature Materials, 2013, vol. 12, pp. 1107-1111. (link)

 

Tandem devices

Both chalcogenide and perovskite absorbers exhibit a wide range of bandgap tunability, which allows for their integration in solution-processed tandem solar cells. By stacking or depositing high bandgap solar cells on top of low bandgap devices the utilization of the solar spectrum can be improved and device efficiencies can be increased by over 40%. The realization of high efficiency, solution-processed tandem devices will dramatically reduce solar electricity prices to approach those of coal or gas.

Selected publications:

  1. A. R. Uhl, A. Rajagopal, J. A. Clark, A. Murray, T. Feurer, S. Buecheler, A. K.-Y. Jen, H. W. Hillhouse, Solution-processed Low-Bandgap CuIn(S,Se)2 Absorbers for High Efficiency Single Junction and Monolithic Chalcopyrite-Perovskite Tandem Solar CellsAdvanced Energy Materials, 2018, 1801254. (link)
  2. I. Braly, R. Stoddard, A. Rajagopal, A. R. Uhl, J. Katahara, A. K.-Y. Jen, and H. W. Hillhouse, Current Induced Phase Segregation in Mixed Halide Hybrid Perovskites and its Impact on Two-Terminal Tandem Solar Cell DesignACS Energy Letters, 2017, vol. 2, pp. 1841-1847. (link)
  3. A. R. Uhl, Z. Yang, A.K.Y. Jen, and H. W. Hillhouse, All solution-processed chalcopyrite – perovskite tandem solar cells in bandgap-matched two-and four-terminal architectures, Journal of Materials Chemistry A, 2017, vol. 5, pp. 3214-3220. (link)

 

Photoelectrochemical devices for solar fuels

High voltages from tandem devices allow their use in catalysis reactions for solar fuels. The photoelectrochemical (PEC) reduction of CO2has received growing attention as a potential solution to the intermittency of solar PV while reducing the amount of excess CO2 in the atmosphere. Solar energy harvested by PV is thereby used to convert CO2 into value-added hydrocarbon chemicals for usable, transportable, and storable fuels. Similar to solar PV, low-cost deposition methods and materials for catalysts and PEC devices are needed to guarantee the growth of the technology as well as cost-competitive solar fuels.

Selected publications:

  1. S. Yun, Y. Qin, A. R. Uhl, V. Nikolaos, M. Yin, D. Li, X. Han, and A. Hagfeldt, Integrated Devices Based on Dye-Sensitized and Perovskite Solar CellsEnergy & Environmental Science, 2018, vol. 11, pp. 476-526. (link)
  2. M. Schreier, F. Héroguel, L. Steier, S. Ahmad, J. S. Luterbacher, M. T. Mayer, J. Luo, and M. Grätzel, Solar conversion of CO2 to CO using Earth-abundant electrocatalysts prepared by atomic layer modification of CuONature Energy, 2017, vol. 2, 17087. (link)

Selected Publications & Presentations

Please find full list on Google Scholar.

Recent peer-reviewed journals

  • E.A. Alharbi, A.Y. Alyamani, D.J. Kubicki, A.R. Uhl, B.J. Walder, A.Q. Alanazi, J. Luo, A. Burgos-Caminal, A. Albadri, H. Albrithen, M.H. Alotaibi, J.-E. Moser, S.M. Zakeeruddin, F. Giordano, L. Emsley, and M. Grätzel, Two-dimensional solid-state NMR unravels molecular level details on the interfacial action of ammonium salts enabling highly efficient and robust perovskite solar cells, Nature Communications, 2019, 10 (1), 3008. (link)
  • Y. Liu, S. Akin, L. Pan, R. Uchida, N. Arora, J. V. Milić, A. Hinderhofer, F. Schreiber, A. R. Uhl, S. M. Zakeeruddin, A. Hagfeldt, M. I. Dar, M. Grätzel, Ultrahydrophobic 3D/2D fluoroarene bilayer-based water-resistant perovskite solar cells with efficiencies exceeding 22%, Science Advances, 2019, 5, eaaw2543. (link)
  • A. R. Uhl, A. Rajagopal, J. A. Clark, A. Murray, T. Feurer, S. Buecheler, A. K.-Y. Jen, H. W. Hillhouse, Solution-processed Low-Bandgap CuIn(S,Se)2 Absorbers for High Efficiency Single Junction and Monolithic Chalcopyrite-Perovskite Tandem Solar Cells, Advanced Energy Materials, 2018, 1801254. (link)
  • S. Yun, Y. Qin, A. R. Uhl, V. Nikolaos, M. Yin, D. Li, X. Han, and A. Hagfeldt, Integrated Devices Based on Dye-Sensitized and Perovskite Solar Cells, Energy & Environmental Science, 2018, vol. 11, pp. 476-526. (link)
  • J. A. Clark, A. R. Uhl, T. R. Martin, and H. W. Hillhouse, Evolution of Morphology and Composition during Annealing and Selenization in Solution-Processed Cu2ZnSn(S,Se)4, Chemistry of Materials, 2017, vol. 29 (21), pp. 9328-9339. (link)
  • I. Braly, R. Stoddard, A. Rajagopal, A. R. Uhl, J. Katahara, A. K.-Y. Jen, and H. W. Hillhouse, Current Induced Phase Segregation in Mixed Halide Hybrid Perovskites and its Impact on Two-Terminal Tandem Solar Cell Design, ACS Energy Letters, 2017, vol. 2, pp. 1841-1847. (link)
  • A. R. Uhl, Z. Yang, A.K.Y. Jen, and H. W. Hillhouse, All solution-processed chalcopyrite – perovskite tandem solar cells in bandgap-matched two-and four-terminal architectures, Journal of Materials Chemistry A, 2017, vol. 5, pp. 3214-3220. (link)
  • A. R. Uhl, J. K. Katahara, and H. W. Hillhouse, Molecular-ink route to 13.0% efficient low-bandgap CuIn(S,Se)2 and 14.7% efficient Cu(In,Ga)(S,Se)2 solar cells, Energy & Environmental Science, 2016, vol. 9, pp. 130-134. (link)
  • H. Xin, S. M. Vorpahl, A. D. Collord, I. L. Braly, A. R. Uhl, B. W. Krueger, D. S. Ginger, and H. W. Hillhouse, Lithium-Doping Affects the Nanoscale Electrical Properties of Grains and Grain Boundaries of Cu2ZnSn(S,Se)4, Physical Chemistry Chemical Physics, 2015, vol. 17, pp. 23859-23866.
  • Y. E. Romanyuk, H. Hagendorfer, P. Stücheli, P. Fuchs, A. R. Uhl, C. M. Sutter-Fella, M. Werner, S. Haass, J. Stückelberger, C. Broussillou, P. Grand, V. Bermudez, and A. N. Tiwari, All Solution-Processed Chalcogenide Solar Cells – From Single Functional Layers Towards a 13.8% Efficient CIGS Device, Advanced Functional Materials, 2015, vol. 25, no. 1, pp. 12-27.

Book chapters

  • A. R. Uhl, Chapter 19: Metal Counter Electrodes for Perovskite Solar Cells, in Counter Electrodes for Dye-Sensitized and Perovskite Solar Cells, Eds. A. Hagfeldt, S. Yun, John Wiley & Sons, Inc., 2018, doi:10.1002/9783527813636.ch17:421-456 (link).

Patents

  • H. W. Hillhouse and A. R. Uhl, Formulation of Molecular Inks for Copper Chalcogenide Semiconductors, 2016, US62/431,305.
  • A. N. Tiwari, Y. E. Romanyuk, A. R. Uhl, and M. Kälin, Process for Producing Light Absorbing Chalcogenide Films, 2012, WO2012107256-A1.

 

 

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