POSS Polyimide Composite Sealed Triple‐Junction GaAs Thin‐Film Solar Cell for Long‐Term Low Earth Orbit Serve

Abstract Polyhedral oligomeric silsesquioxane (POSS) polyimide is promising for sealing flexible photoelectronic devices for space applications. However, atomic oxygen interaction with POSS polyimide results in a porous SiO _x passivating layer, ultraviolet interaction results in bonding degradation, both causing the transmittance decrease in the visible light range. In this study, the atomic oxygen exposure‐induced transmittance decrease of POSS polyimide is explained and simulated by Rayleigh scattering. Ultrathin oxide films and ultraviolet absorbent are introduced to POSS polyimide by surface‐ and bulk‐phase modifications to improve atomic oxygen and ultraviolet resistance, which achieves ≈0 wt% mass loss upon an eight‐year long‐term atomic oxygen exposure and is deduced by molecular dynamics. The atomic oxygen exposure effect on the sheet resistance of flexible conductive indium tin oxide‐POSS polyimide is explained by band structure calculation. The SiO ₂ ‐POSS polyimide sealed triple‐junction GaAs thin‐film solar cell exhibits beginning of life (BOL) and end of life (EOL) efficiencies of 27.67% and 23.38% upon an eight‐year long‐term to atomic oxygen. The atomic oxygen reactions with polyimide‐based films are explained by zero‐ and first‐order reactions, and predictive formulas are created for the film mass loss and sealed solar cell performance under the long‐term atomic oxygen exposure. This study suggests a POSS polyimide composite as a packaging film for flexible photoelectronic devices in low Earth orbit.