GaSb‐Based Solar Cells for Full Solar Spectrum Energy Harvesting

TLDR

The study develops a GaSb‑based multijunction solar cell that captures long‑wavelength photons normally lost in conventional multijunction designs. Using modeling, experimental optimization, and transfer‑printing, the authors stack a GaAs triple‑junction cell with a GaSb/InGaAsSb concentrator to form a four‑terminal, five‑junction device covering >99 % of the Sun’s direct‑beam spectrum. The assembled mini‑module achieves an outdoor module efficiency of 41.2 % and an implied cell efficiency of 44.5 % under a 744‑sun concentration ratio.

Abstract

Abstract In this work, a multijunction solar cell is developed on a GaSb substrate that can efficiently convert the long‐wavelength photons typically lost in a multijunction solar cell into electricity. A combination of modeling and experimental device development is used to optimize the performance of a dual junction GaSb/InGaAsSb concentrator solar cell. Using transfer printing, a commercially available GaAs‐based triple junction cell is stacked mechanically with the GaSb‐based materials to create a four‐terminal, five junction cell with a spectral response range covering the region containing >99% of the available direct‐beam power from the Sun reaching the surface of the Earth. The cell is assembled in a mini‐module with a geometric concentration ratio of 744 suns on a two‐axis tracking system and demonstrated a combined module efficiency of 41.2%, measured outdoors in Durham, NC. Taking into account the measured transmission of the optics gives an implied cell efficiency of 44.5%.