Tommy Richards

After almost two decades of being the industry standard for space-based power generation, legacy silicon solar cells were slowly replaced by GaAs-based solar cells from 1977, due to their superior efficiencies and radiation resistances. Since then, modern silicon solar cells for terrestrial applications have advanced significantly with silicon heterojunction and perovskite/silicon tandem cells reaching impressive heights with record efficiencies of 27.8% and 34.85% in AM1.5G. Hence, modern silicon-based solar cells are now being re-evaluated for space power generation. Even though using modern silicon solar cells would currently reduce the beginning of life power output density by around 28% and, for a given coverglass thickness they are 2.6 times less radiation resistant than triple-junction devices, the cost savings could be as large as 85-90% with the major upfront cost coming from the price of the space qualified coverglass, rather than the silicon cell itself.

This paper will review silicon solar cell structures, the history of silicon solar cells in space and the effects of the space environment, with a focus on charged-particle radiation, thermal effects, and UV light. Areas for future research on enhancing radiation resilience and improving maximum efficiencies are also presented with the aim that silicon-based solar cells will make a significant return to space soon.

Perovskite solar cells (PSCs) are promising candidates for space applications due to their high efficiency, radiation tolerance, and high power-to-mass ratio. However, the harsh space environment introduces stressors such as thermal shock (TS) from rapid temperature transitions in orbit, a degradation mode that remains underexplored. This study investigated the real operating temperature profiles experienced by solar cells orbiting in low Earth orbit, revealing rapid and extreme temperature transitions. Based on these findings, we developed an accelerated TS testing protocol, cycling PSC devices between −80 °C and +80 °C at a rapid ramp rate of 16 °C min−1 for 100 cycles, designed to replicate and amplify the stresses induced by actual orbital thermal cycles. Using FAPbI3 as a model system, we explored the impact of varying concentrations of MAPbBr3 (0–7%) on the perovskite film's structural stability under this accelerated TS. Our results indicate that an intermediate MAPbBr3 incorporation level (specifically 5%) most effectively suppresses microstrain and the formation of the detrimental δ-phase after TS exposure. To validate our laboratory findings under near-space conditions, we conducted a comparative high-altitude balloon test at 35 km. These findings establish TS as a critical testing framework for evaluating PSC stability in space applications and highlight the necessity of refining material compositions for space applications.

The rapid expansion of space-based initiatives and the increasing deployment of satellites have intensified the demand for high-performance, radiation-tolerant photovoltaics (PV). This study investigates the radiation tolerance of all-inorganic CsPbI3 perovskites for space PV applications. Combining simulations and experimental evaluations, we compare the properties of CsPbI3 films depending on the surface treatments using long chain cations. Octylammonium iodide (OAI) treatment forms a quasi-2D perovskite structure, whereas phenethylammonium iodide (PEAI) induces a molecular cation layer. Under harsh proton irradiation (2 × 1014 protons/cm2 at 0.05 MeV), OAI-treated devices exhibited only a 19% efficiency reduction, significantly lower than the performance degradation observed in organic–inorganic hybrid perovskite PVs. Moreover, OAI treatment does not have adverse effects after irradiation, while the PEAI layer results in a severe deviation in surface electrical potential following irradiation. These findings suggest new directions for using all-inorganic PSCs in high-radiation environments, prompting further investigation into next-generation space PV technologies.

Ultrawide-bandgap (UWBG, Eg ≥ 1.8 eV) perovskites serve as indispensable top-cell absorbers in perovskite–perovskite–silicon (PPS) triple-junction (TJ) configurations and play a decisive role in approaching the theoretical efficiency limit of approximately 49.6%. Halide mixing, such as incorporation of Br− or Cl−, is a conventional approach to widen the bandgap; however, it causes thermodynamic instabilities due to their high mixing enthalpies and pronounced lattice distortion. While such instabilities are also observed in conventional wide-bandgap (WBG, Eg ≥ 1.65 eV) perovskites, they are significantly exacerbated in UWBG compositions, leading to accelerated light-induced phase segregation, lattice strain, acceleration of ion migration, and generation of nonradiative recombination sites. This review focuses on the thermodynamic, structural, and interfacial origins of instability in UWBG perovskites and systematically analyzes the stabilization strategies proposed to overcome these limitations. It further discusses how these strategies are implemented in perovskite–perovskite–silicon (PPS) triple-junction solar cells (TJSCs) to enhance device performance and operational stability and outlines future research directions toward realizing high-efficiency, long-term-stable UWBG top cells and PPS TJSCs.