Wide spectral coverage (0.7–2.2 eV) lattice‐matched multijunction solar cells based on AlGaInP, AlGaAs and GaInNAsSb materials

Abstract

We report on the progress in developing lattice-matched GaAs-based solar cells with focus on developing AlGaInP, AlGaAs, and GaInNAsSb materials, aiming at achieving a wide spectral coverage, that is, 0.7-2.2 eV. To this end, we first benchmark the performance of an upright four-junction GaInP/GaAs/GaInNAsSb/GaInNAsSb solar cells grown by molecular beam epitaxy on p-GaAs substrates with bandgaps of 1.88, 1.42, 1.17, and 0.93 eV, respectively. The four-junction cell exhibited an efficiency of 39% at 560-sun illumination while showing good electrical performance even up to 1000 suns. As a first step to further improve the efficiency toward 50% level, we demonstrate AlGaInP (>2 eV) and GaInNAsSb (<0.8 eV) subcells. We prove that AlGaInP cells with 0.1 Al composition would exhibit current-matching condition when being incorporated in a five-junction architecture together with two GaInNAsSb bottom and AlGaAs top junctions. Furthermore, current matching required for a six-junction tandem architecture is achieved for an Al composition of 0.26. Overall, the results open a practical path toward fabrication of lattice-matched solar cells with more than four junctions.

Facile Substrate-Agnostic Preparation of High-Performance Regenerative Water Splitting (Photo)electrodes

“…To broaden the scope of this technique, we also demonstrated its use as stabilizing cocatalysts for III–V semiconductor-based photoelectrode devices. While III–V semiconductors have demonstrated record levels of efficiency in photovoltaic (PV) and PEC water splitting cells, − the challenge is to stabilize III–V semiconductors from photocorrosion in harsh electrolyte environments. − Here, we demonstrated this method using a commercial single-junction GaAs PV cell to fabricate a decoupled photoanode device for PEC water splitting. GaAs is selected due to its direct band gap (1.42 eV) which is close to the ideal band gap for optimal solar absorption. , At the same time, we use a decoupled photoanode scheme here due to the attractive proposition of physically separating the light-harvesting and catalytic components to the front and rear device areas, respectively, which permits the use of nontransparent cocatalysts at the rear .…”

Optical Performance Assessment of Nanostructured Alumina Multilayer Antireflective Coatings Used in III–V Multijunction Solar Cells

“…With the nano-ARC, a great portion of the photons at a bandwidth of 1380–1800 nm could be utilized and at AM0 that corresponds to a current density of ∼12.6 mA/cm 2 . This is slightly lower than the current densities of the other junctions, so having an additional 0.7 eV subcell, i.e., third GaInNAsSb, 34 would require either altering the subcell bandgaps of the current design or adding a topmost junction, such as AlGaInP, 35 to provide nearly current-matched five or six junction SCs for space applications.…”

The fabrication of flexible and large‐size inverted metamorphic five‐junction solar cells

“…5,6 The photoelectric conversion efficiency of single junction solar cell is limited by the Shockley-Queisser (S-Q) limit, while the multijunction solar cells that are vertically stacked of different materials with different bandgap energies are introduced to further improve the photoelectric conversion efficiency. 7,8 In theory, the more junctions a solar cell has, the higher its efficiency. The non-concentration efficiency of solar cells with the above three junctions is expected to exceed 40%.…”