Engineering the Reciprocal Space for Ultrathin GaAs Solar Cells

Jeronimo Buencuerpo, Jose Llorens, Jose Ripalda, Myles Steiner, Adele Tamboli

Research output: Contribution to journalArticlepeer-review

10 Scopus Citations

Abstract

III-V solar cells dominate the high efficiency charts, but with significantly higher cost than other solar cells. Ultrathin III-V solar cells can exhibit lower production costs and immunity to short carrier diffusion lengths caused by radiation damage, dislocations, or native defects. Nevertheless, solving the incomplete optical absorption of sub-micron layers presents a challenge for light-trapping structures. Simple photonic crystals have high diffractive efficiencies, which are excellent for narrow-band applications. Random structures offer a broadband response instead but suffer from low diffraction efficiencies. Quasirandom (hyperuniform) structures lie in between, providing high diffractive efficiency over a target wavelength range, which is broader than simple photonic crystals, but narrower than a random structure. In this work, we present a design method to evolve a simple photonic crystal into a quasirandom structure by modifying the spatial-Fourier space in a controlled manner. We apply these structures to an ultrathin GaAs solar cell of only 100 nm. We predict a photocurrent for the tested quasirandom structure of 25.3 mA/cm2, while a planar structure would be limited to 16.1 mA/cm2. The modified spatial-Fourier space in the quasirandom structure increases the amount of resonances, with a progression from discrete number of peaks to a continuum in the absorption. The enhancement in photocurrent is stable under angle variations because of this continuum. We also explore the robustness against changes in the real-space distribution of the quasirandom structures using different numerical seeds, simulating variations in a self-assembly method. We observe a standard deviation of the quasirandom structures of only 0.3 mA/cm2. The approach presented here can be applied to guide future optimizations and experimental design and fabrication of new classes of photonic crystals for GaAs and other ultrathin solar cells.

Original languageAmerican English
Article number107224
Number of pages9
JournalOptics and Laser Technology
Volume142
DOIs
StatePublished - Oct 2021

Bibliographical note

Publisher Copyright:
© 2021 Elsevier Ltd

NREL Publication Number

  • NREL/JA-5900-77490

Keywords

  • Photonic crystals
  • Quasi-random
  • Solar cells
  • Ultrathin

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