Electron radiation-induced degradation of silicon solar cells

Silicon solar cells have attracted increasing interest for space exploration due to their significant cost-effectiveness compared to other photovoltaic technologies. However, performance of current commercial silicon solar cell architectures under space conditions, such as electron irradiation, has not been investigated. This work evaluates the electrical performance of n-type lifetime wafers and state-of-the-art silicon solar cells, including p-type passivated emitter and rear contact (PERC) and n-/p-type tunnel oxide passivated contact (TOPCon) silicon solar cells, after electron irradiation. These samples were irradiated under varying doses of 1-MeV electrons and 2.16 × 10 14 e/cm 2 of 5-MeV electrons. Post-radiation characterisation reveals a significant reduction in minority carrier lifetime, which was predominantly attributed to the bulk lifetime degradation from ∼75,000 μ s to ∼240 μ s after 10 12 e/cm 2 and further to ∼0.2 μ s after 10 15 e/cm 2 of 1-MeV electron irradiation. Corresponding to the reduction in bulk lifetime, the integrated external quantum efficiency (EQE) decreased by 27.5 % for p-PERC and 33.3 % for n-TOPCon solar cells relative to their initial value. Furthermore, defect characterisation using the defect parameterisation solution space (DPSS) method identifies the vacancy-vacancy as the dominant radiation-induced defect. Ultimately, comparative analysis with actual space mission data suggests that the observed degradation under 5 × 10 14 e/cm 2 , 1-MeV electron irradiation is comparable to 3-5 years of low Earth orbit (LEO) space conditions. These findings underscore the critical role of minority bulk carrier lifetime degradation in limiting the performance of silicon solar cells under a space radiation environment, and highlight the need for enhanced radiation tolerance in commercial space silicon solar cells. • Analysed bulk lifetime degradation in n-TOPCon wafers after electron irradiation using IDLS and PL imaging. • Identified di-vacancies as dominant radiation-induced defects via DPSS and TIDLS methods. • Compared I-V and EQE losses in radiated n-/p-TOPCon, and p-PERC solar cells, showing bulk lifetime degradation as main loss cause. • Modelled the impact of bulk lifetime degradation on I–V performance and EQE response using Quokka 3 simulations. • Correlated lab radiation results with LEO spaceflight data, estimating 3–5 years equivalent damage depending on encapsulation.