Gallium–Lithium co‐doped Silicon Heterojunction Solar Cells for Irradiation‐Induced Defects Mitigation

Thin (85 µm) p‐type silicon heterojunction (SHJ) solar cells featuring post‐irradiation recovery effects have been prepared through the addition of lithium (Li) in a gallium (Ga)‐doped substrate. The compatibility of modern SHJ solar cells with Ga–Li co‐doped silicon has been firstly demonstrated, with conversion efficiency values equivalent to those of reference (without Li) devices and an AM1.5 V oc value of 748 mV for a sample featuring a Li concentration of 6 × 10 15 cm −3 . Then the SHJ solar cells have been submitted to 1 MeV electron irradiation at fluences of 5 × 10 13 and 1 × 10 14 e⋅cm −2 . Slight changes have been highlighted in the post‐irradiation efficiencies between the reference and the Li‐rich cells, which are related to p 0 variations with Li addition. Prolonged illumination tests (AM0–1367 W⋅m −2 ) at temperatures of 80 and 100 °C lead to significant recovery effects for the Li‐rich SHJ solar cells, whereas the reference cells feature only limited recovery capabilities. For the lower fluence, a strong V oc regeneration (superior to 140 mV) is observed, bringing the V oc close to the pre‐irradiation value. For the Li‐rich samples, these recovery effects result in efficiency gains of almost 4.0% abs and 3.5% abs for the 5 × 10 13 and 1 × 10 14 e⋅cm −2 irradiated samples, respectively.