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Optoelectronic Materials

The M3 research team

Dr. Monica Morales-Masis ( )

Our research focusses on the controlled synthesis, development and understanding of novel materials and thin films with functional optical and electrical properties. These materials and thin films find application in state of the art optoelectronic devices such as solar cells, LEDs, transparent electronics, photonics and other energy efficient devices. We work on three main research lines: 1. Transparent conducting oxides (TCOs), 2. P-type transparent material discovery and 3. Hybrid and full-inorganic halide perovskites.


TCOs for Solar Cells

TCOs are essential in solar cells with resistive absorbers, such as the case of the silicon heterojunction solar cells and perovskite-based solar cells. To allow the maximum amount of sunlight into the cells, the front TCO should be transparent from the UV to the NIR; and to guarantee unhindered carrier extraction, the TCO should have high lateral conductivity and low contact resistance with the adjacent layers of the device. This is a challenge, due to the intrinsic trade-off between transparency and conductivity. Another challenge is the deposition of the TCO without damaging the exposed layers of the solar cells during growth. All these requirements motivate the search for material compositions and synthesis of TCOs, that lead to optimum conductivity and broadband transparency, for example by achieving high electron mobilities, while avoiding damage to the device by performing a gentle, soft-landing deposition. One of the techniques we are exploring for this is pulsed-laser deposition (PLD). The materials we are currently studying are zirconium-doped indium oxide (In2O3:Zr) and lanthanum-doped barium-stannate  (LaBaSnO3), both wide band-gap and high-mobility materials.

P-type Transparent Material Discovery

Most TCOs and oxides known to date are n-type. The challenge for p-type conductivity in oxides originates from a highly-localized oxygen 2p valence band (low hole mobilities) and the positioning of the valence band well below the vacuum level (high ionization potentials). Recent computational predictions indicate that a transition from a metal oxide to a metal oxychalcogenide or chalcogenide could solve the challenge of valence band delocalization, lowering the hole effective mass and increasing hole mobility. We are exploring this hypothesis by synthesizing the materials and characterizing the optoelectronic and compositional properties to determine the most promising e.g. oxysulfide compositions and optimize them for application as p-type contacts in solar cells.

CREATE: Crafting Complex Hybrid Materials for Sustainable Energy Conversion (ERC funded project)

Pulsed Laser Deposition (PLD) has offered unique options for the development of complex materials thin film growth, allowing stoichiometric transfer and multi-compound deposition independent of the relative volatility of the elements. We are exploring the potential of PLD as a single-source, solvent free deposition method of inorganic multi-compound halide perovskite thin films. Moreover, we are developing a unique in-vacuum dual source laser-based deposition method that decouples the deposition of the organic and inorganic sources during growth. This allows the exploration of a breadth of organic-inorganic halide perovskite compositions, paving the way for discovering new, non-toxic, stable materials for efficient solar cells, LEDs and beyond.

The M3 team

  • Dr. Monica Morales Masis (PI – right on the picture)
  • Yury Smirnov (Yura) (PhD Student – second from the left to right)
  • Tatiana Soto-Montero (PhD Student – first from the left to right)
  • Nathan Rodkey (visiting PhD Student – fifth from the left to right)
  • Pierre-Alexis Repecaud (Postdoc – fourth from the left to right)
  • Stan Kaal (MSc Student – third from the left)

Former members:

  • Eloy Marcelis (BSc Student)
  • Riemer Kuik (BSc Student)
  • Stef Wassens (BSc Student)
  • Laura Schmengler (MSc Student)
  • Vivien Kiyek (MSc Student)




Main Publications

  1. Fioretti, A.N., Morales-Masis, M., 'Bridging the p-type transparent conductive materials gap: synthesis approaches for disperse valence band materials' J. of Photonics for Energy, 10(4) (2020).
  2. Morales-Masis, M. et al., “Transparent Electrodes for Efficient OptoelectronicsAdv. Electron. Mater. Vol. 3 (2017).
  3. Rucavado, E., Landucci, F., Döbeli, M., Jeangros, Q., Boccard, M., Hessler-Wyser, A., Ballif, C., Morales-Masis, M., “Zr-doped indium oxide electrodes: Annealing and thickness effects on microstructure and carrier transport”, Phys. Rev. Materials, 3 (2019).
  4. Ayding E., De Bastiani M., Yang X., Sajjad M., Aljamaan F., Smirnov Y., Nejib Hedhili M., Liu W., Allen T. G., Xu L., Van Kerschaver E., Morales‐Masis M., Schwingenschlögl U., De Wolf S. "Zr‐Doped Indium Oxide (IZRO) Transparent Electrodes for Perovskite‐Based Tandem Solar Cells’’ Adv. Funct. Mater., 29 (25) (2019).
  5. Rucavado, E., Graužinytė, M., Flores-Livas, J.; Jeangros, Q., Landucci, F., Lee, Y., Koida, T., Goedecker, S., Hessler-Wyser, A., Ballif, C., Morales-Masis, M. “New Route for “Cold-Passivation" of Defects in Tin-Based Transparent Conductive OxidesThe Journal of Physical Chemistry C, 122 (31) (2018).
  6. Morales-Masis M., Rucavado E., Monnard R., Barraud L., Holovsky J., Despeisse M., Ballif C. “Highly Conductive and Broadband Transparent Zr-doped In2O3 as Front Electrode for Solar CellsIEEE Journal of Photovoltaics, 8 (5) (2018). 
  7. Zhong S., Morales-Masis M., Mews M., Korte L., Jeangros Q., Wu W., Boccard M., Ballif C. “Exploring co-sputtering of ZnO: Al and SiO2 for efficient electron-selective contacts on silicon solar cells”, Solar Energy Materials and Solar Cells, 194 (2019).
  8. Ingenito, A., Nogay, G., Jeangros, Q., Rucavado, E., Allebé, C., Eswara, S., Valle, N., Wirtz, T., Horzel, J., Koida, T., Morales-Masis, M., Despeisse, M., Haug, F.-J., Löper, P., Ballif, C. “A passivating contact for silicon solar cells formed during a single firing thermal annealingNature Energy, 3 (9) (2018).
  9. Essig S., Dréon J., Rucavado E., Mews M., Koida T., Boccard M., Werner J., Geissbühler J., Löper P., Morales-Masis M., Korte L., De Wolf S., Ballif C. “Toward Annealing-Stable Molybdenum-Oxide-Based Hole-Selective Contacts For Silicon PhotovoltaicsSolar RRL, 2 (4) (2018).
  10. Bullock, J., Ota, H., Wang, H., Xu, Z., Hettick, M., Yan, D., Samundsett, C., Wan, Y., Essig, S., Morales-Masis, M., Cuevas, A., Javey, A. “Microchannel contacting of crystalline silicon solar cells” Scientific Reports, 7 (9085) (2017).
  11. Rucavado, E., Jeangros, Q., Urban, D.F., Holovský, J., Remes, Z., Duchamp, M., Landucci, F., Dunin-Borkowski, R.E., Körner, W., Elsässer, C., Hessler-Wyser, A., Morales-Masis, M., Ballif, C. “Enhancing the optoelectronic properties of amorphous zinc tin oxide by subgap defect passivation: A theoretical and experimental demonstrationPhysical Review B, 95 (24) (2017).  
  12. M. Morales-Masis et al., “An Indium-Free Anode for Large-Area Flexible OLEDs: Defect-Free Transparent Conductive Zinc Tin Oxide,” Adv. Funct. Mater., vol. 26, no. 3, (2016).