A multifunctional anti-reflection coating on coverglass for III-V solar cells for space applications

This is the authors' abstract. We don't add key points for this paper.

Solar photovoltaic (PV) cells are used to power satellites in space, and incorporate ultra-thin (∼150 μm), radiation-tolerant coverglass sheets to provide protection and mechanical support. Optical coatings can be applied to this coverglass surface, such as anti-reflection coatings to reduce reflection losses, typically a single layer of MgF 2 , which has limitations such as poor durability and lack of thermal management. Optical coatings can also contribute to passive cooling, reducing cell operating temperatures in the space environment where large temperature swings are present. This work details the design, deposition and characterisation of a multilayer, multifunctional coating comprising metal-oxide dielectrics (SiO 2 , HfO 2 , Nb 2 O 5 ), to provide anti-reflection for a single-junction III-V solar cell such as GaAs or InP, increasing power output, with UV and IR reflection as well as high emissivity to provide passive cooling. The multifunctional coating reduces weighted average reflectance (WAR) by 2.48% across 400 - 870 nm, with IR reflection peaking at over 60%, and UV reflectance peaking at over 80%. A temperature reduction of approximately 13 K under one sun AM0 is predicted, and a total relative increase in efficiency of 4.4% for a single-junction GaAs device, compared to uncoated coverglass. Durability testing shows the coating is resistant to UV and damp heat, mechanical abrasion, and proton irradiation. Displacement Damage Dose modelling predicts significant improvement in shielding against proton damage across LEO (Starlink), Molniya, and GEO orbits. The multifunctional coating can be adapted to all PV technologies for space applications, to provide improved power output and increased mission lifetime.