Designing a hybrid thin-film/wafer silicon triple photovoltaic junction for solar water splitting

Paula Perez-Rodriguez, Wouter Vijselaar, Jurriaan Huskens, Machiel Stam, Michael Falkenberg, Miro Zeman, Wilson Smith, Arno H.M. Smets

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
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Abstract

Solar fuels are a promising way to store solar energy seasonally. This paper proposes an earth-abundant heterostructure to split water using a photovoltaic-electrochemical device (PV-EC). The heterostructure is based on a hybrid architecture of a thin-film (TF) silicon tandem on top of a c-Si wafer (W) heterojunction solar cell (a-Si:H (TF)/nc-Si:H (TF)/c-Si(W)) The multijunction approach allows to reach enough photovoltage for water splitting, while maximizing the spectrum utilization. However, this unique approach also poses challenges, including the design of effective tunneling recombination junctions (TRJ) and the light management of the cell. Regarding the TRJs, the solar cell performance is improved by increasing the n-layer doping of the middle cell. The light management can be improved by using hydrogenated indium oxide (IOH) as transparent conductive oxide (TCO). Finally, other light management techniques such as substrate texturing or absorber bandgap engineering were applied to enhance the current density. A correlation was observed between improvements in light management by conventional surface texturing and a reduced nc-Si:H absorber material quality. The final cell developed in this work is a flat structure, using a top absorber layer consisting of a high bandgap a-Si:H. This triple junction cell achieved a PV efficiency of 10.57%, with a fill factor of 0.60, an open-circuit voltage of 2.03 V and a short-circuit current density of 8.65 mA/cm 2 . When this cell was connected to an IrO x /Pt electrolyser, a stable solar-to-hydrogen (STH) efficiency of 8.3% was achieved and maintained for 10 hours.

Original languageEnglish
Pages (from-to)245-254
Number of pages10
JournalProgress in Photovoltaics: research and applications
Volume27
Issue number3
DOIs
Publication statusPublished - 2019

Keywords

  • electrolysis
  • heterostructures
  • hydrogen fuel
  • multijunction
  • open-circuit voltage
  • photovoltaic

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