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The promise of solution-processed Fe2GeS4 thin films in iron chalcogenide photovoltaics


The olivine Fe2GeS4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe2GeS4 precursor powders obtained via a simple solution-based process were converted to highly crystalline Fe2GeS4 powders upon a thermal treatment in controlled atmosphere. Thin films fabricated by dip coating in the Fe2GeS4 precursor dispersion and subjected to the same thermal treatment render high-purity Fe2GeS4 thin films with a band gap of 1.4 eV, measured by room-temperature photoluminescence. Using Fe2GeS4 thin films as the sole absorber in a solution-based solar cell, open-circuit voltages of 361 mV are observed, while the use of the Fe2GeS4 films as counter electrodes in dye-sensitized solar cell constructs enhances the overall power conversion efficiency of the cell by a factor of five. This is the first report of a photovoltaic device based on Fe2GeS4.

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This material is based upon work supported in part by the US Department of Energy SunShot Initiative (Award DE-EE0006322) and the National Science Foundation (Grants 1458980 and 1435716). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, was supported by the US Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. The authors would like to thank Dr. William Shafarman at the Institute of Energy Conversion at University of Delaware for valuable discussions regarding the solar cell results and to Dr. Susanne Siebentritt and Dr. Philip Dale for access to their research facilities.

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Correspondence to Daniela R. Radu.

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Liu, M., Berg, D.M., Hwang, PY. et al. The promise of solution-processed Fe2GeS4 thin films in iron chalcogenide photovoltaics. J Mater Sci 53, 7725–7734 (2018).

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  • Precursor Powder
  • Power Conversion Efficiency
  • Dye-sensitized Solar Cells (DSSC)
  • Open-circuit Voltage
  • Atomic Percentage Ratio