Design perspectives of a thin film GaAs solar cell integrated with Carrier Selective contacts and anti-reflection coatings: Optical and device analysis

Abstract

III-V thin-film solar cells (SCs) have shown exceptional optoelectronic properties and remarkable power conversion efficiency (PCE), attributed to their outstanding charge transport, efficient photon trapping, adaptability, and recycling of photons. In particular, incorporating anti-reflective coatings (ARCs) made from wide-bandgap oxides has proven effective in reducing optical losses, with reductions as low as 20 % being reported. Furthermore, the use of carrier-selective contacts in these designs not only eliminates the need for complex doped junctions but also simplifies the fabrication process, further enhancing their performance. Despite these advancements, relatively few studies have explored the integration of both ARCs and carrier-selective contacts in gallium arsenide (GaAs)-based thin-film solar cells. This gap represents a significant opportunity for improving the efficiency and performance of these devices. To address this, we present a GaAs thin-film solar cell incorporating an ARC layer for enhanced light-trapping and optimized photon absorption. In addition, we integrate carrier-selective contacts using titanium dioxide (TiO₂) as the electron transport layer and molybdenum oxide (MoO₃) as the hole transport layer, ensuring effective charge separation and collection. Our optical analysis demonstrates that, with an optimized ARC thickness, the optical losses in the 380 nm-thick GaAs absorber layer can be limited to 20 %. Moreover, by maintaining a surface recombination velocity (SRV) of 10³ cm/s and a carrier lifetime of 10μs, the proposed design achieves an impressive PCE of approximately 23 %. This study highlights the potential of combining ARCs and carrier-selective contacts to push the performance of GaAs thin-film solar cells to new heights, paving the way for more efficient, and cost-effective photovoltaic technologies.