Bio


Renewable energy will power the future of the world. I work on R&D of a promising new solar cell technology based on perovskite semiconductors. My interests - semiconductor device physics, solar cell engineering, inorganic chemistry, and experimental data analysis.

All Publications


  • Band Gap Tuning via Lattice Contraction and Octahedral Tilting in Perovskite Materials for Photovoltaics Journal of the American Chemical Society Prasanna, R., Gold-Parker, A., Leijtens, T., Conings, B., Babayigit, A., Boyen, H., Toney, M. F., McGehee, M. D. 2017; 139 (32)

    View details for DOI 10.1021/jacs.7b04981

  • Perovskite-perovskite tandem photovoltaics with optimized band gaps SCIENCE Eperon, G. E., Leijtens, T., Bush, K. A., Prasanna, R., Green, T., Wang, J. T., McMeekin, D. P., Volonakis, G., Milot, R. L., May, R., Palmstrom, A., Slotcavage, D. J., Belisle, R. A., Patel, J. B., Parrott, E. S., Sutton, R. J., Ma, W., Moghadam, F., Conings, B., Babayigit, A., Boyen, H., Bent, S., Giustino, F., Herz, L. M., Johnston, M. B., McGehee, M. D., Snaith, H. J. 2016; 354 (6314): 861-865

    Abstract

    We demonstrate four- and two-terminal perovskite-perovskite tandem solar cells with ideally matched band gaps. We develop an infrared-absorbing 1.2-electron volt band-gap perovskite, FA0.75Cs0.25Sn0.5Pb0.5I3, that can deliver 14.8% efficiency. By combining this material with a wider-band gap FA0.83Cs0.17Pb(I0.5Br0.5)3 material, we achieve monolithic two-terminal tandem efficiencies of 17.0% with >1.65-volt open-circuit voltage. We also make mechanically stacked four-terminal tandem cells and obtain 20.3% efficiency. Notably, we find that our infrared-absorbing perovskite cells exhibit excellent thermal and atmospheric stability, not previously achieved for Sn-based perovskites. This device architecture and materials set will enable "all-perovskite" thin-film solar cells to reach the highest efficiencies in the long term at the lowest costs.

    View details for DOI 10.1126/science.aaf9717

    View details for Web of Science ID 000388531900034

    View details for PubMedID 27856902

  • Tin-lead halide perovskites with improved thermal and air stability for efficient all-perovskite tandem solar cells SUSTAINABLE ENERGY & FUELS Leijtens, T., Prasanna, R., Bush, K. A., Eperon, G. E., Raiford, J. A., Gold-Parker, A., Wolf, E. J., Swifter, S. A., Boyd, C. C., Wang, H., Toney, M. F., Bent, S. F., McGehee, M. D. 2018; 2 (11): 2450–59

    View details for DOI 10.1039/c8se00314a

    View details for Web of Science ID 000448425900009

  • Opportunities and challenges for tandem solar cells using metal halide perovskite semiconductors NATURE ENERGY Leijtens, T., Bush, K. A., Prasanna, R., McGehee, M. D. 2018; 3 (10): 828–38
  • Minimizing Current and Voltage Losses to Reach 25% Efficient Monolithic Two-Termina Perovskite-Silicon Tandem Solar Cells ACS ENERGY LETTERS Bush, K. A., Manzoor, S., Frohna, K., Yu, Z. J., Raiford, J. A., Palmstrom, A. F., Wang, H., Prasanna, R., Bent, S. F., Holman, Z. C., McGehee, M. D. 2018; 3 (9): 2173–80
  • Interfacial Effects of Tin Oxide Atomic Layer Deposition in Metal Halide Perovskite Photovoltaics ADVANCED ENERGY MATERIALS Palmstrom, A. F., Raiford, J. A., Prasanna, R., Bush, K. A., Sponseller, M., Cheacharoen, R., Minichetti, M. C., Bergsman, D. S., Leijtens, T., Wang, H., Bulovic, V., McGehee, M. D., Bent, S. F. 2018; 8 (23)
  • Barrier Design to Prevent Metal-Induced Degradation and Improve Thermal Stability in Perovskite Solar Cells ACS ENERGY LETTERS Boyd, C. C., Cheacharoen, R., Bush, K. A., Prasanna, R., Leijtens, T., McGehee, M. D. 2018; 3 (7): 1772–78
  • Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling ADVANCED MATERIALS Guzelturk, B., Belisle, R. A., Smith, M. D., Bruening, K., Prasanna, R., Yuan, Y., Gopalan, V., Tassone, C. J., Karunadasa, H. I., McGehee, M. D., Lindenberg, A. M. 2018; 30 (11)

    Abstract

    Unusual photophysical properties of organic-inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH3 NH3 PbI3 ) following photoexcitation, enabling an ultrafast probe of charge separation, hot-carrier transport, and carrier-lattice coupling under 1-sun-equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hot and band-edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot-carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz-frequency lattice distortions, associated with reorganizations of the lead-iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier-lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far-above-gap photoexcitation. This study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport.

    View details for DOI 10.1002/adma.201704737

    View details for Web of Science ID 000427111300002

    View details for PubMedID 29359820

  • Compositional Engineering for Efficient Wide Band Gap Perovskites with Improved Stability to Photoinduced Phase Segregation ACS ENERGY LETTERS Bush, K. A., Frohna, K., Prasanna, R., Beal, R. E., Leijtens, T., Swifter, S. A., McGehee, M. D. 2018; 3 (2): 428–35
  • Mechanism of Tin Oxidation and Stabilization by Lead Substitution in Tin Halide Perovskites ACS Energy Letters Leijtens, T., Prasanna, R., Gold-Parker, A., Toney, M. F., McGehee, M. D. 2017; 2 (9): 2159
  • Trade-Off between Trap Filling, Trap Creation, and Charge Recombination Results in Performance Increase at Ultralow Doping Levels in Bulk Heterojunction Solar Cells ADVANCED ENERGY MATERIALS Shang, Z., Heumueller, T., Prasanna, R., Burkhard, G. F., Naab, B. D., Bao, Z., McGehee, M. D., Salleo, A. 2016; 6 (24)
  • Minimal Effect of the Hole-Transport Material Ionization Potential on the Open-Circuit Voltage of Perovskite Solar Cells ACS ENERGY LETTERS Belisle, R. A., Jain, P., Prasanna, R., Leijtens, T., McGehee, M. D. 2016; 1 (3): 556-560
  • How the Energetic Landscape in the Mixed Phase of Organic Bulk Heterojunction Solar Cells Evolves with Fullerene Content JOURNAL OF PHYSICAL CHEMISTRY C Sweetnam, S., Prasanna, R., Burke, T. M., Bartelt, J. A., McGehee, M. D. 2016; 120 (12): 6427-6434