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Radiation-Induced Degradation Mechanisms in Thin-Film Multiple-Quantum-Well Solar Cells With Wavelength-Selective Photonic Structures

The radiation-induced degradation in photovoltaic properties of an advanced III–V solar cell structure has been measured and analyzed with a modified 1-D analytical drift-diffusion model. Single-junction GaAs-based thin-film solar cells have been fabricated using MicroLink Devices’ epitaxial liftoff (ELO) process and characterized before and after irradiation. Thinning the GaAs base layer, adding a wavelength-selective photonic structure (WSPS), and incorporating multiple InGaAs quantum wells into an extended junction intrinsic region result in short-circuit current density (Jsc) degradation of just 3% after exposure to a displacement damage dose (DDD) of 2.7 × 1010 MeV/g. No discernable degradation is observed in the infrared external quantum efficiency (EQE) associated with the multiple-quantum-well region, which effectively boosts both the beginning-of-life and end-of-life current collection. The measured changes in Jsc, diode parameters (Jo1, Jo2), open-circuit voltage (Voc), fill factor, and efficiency (η) with increasing DDD levels are well fit after modifying standard models to include additional radiation-induced degradation mechanisms.