Atomic structure of defect responsible for light-induced efficiency loss in silicon solar cells in warmer climates

• Published in: Cell reports physical science 2023-01, Vol.4 (1), p.101201, Article 101201
• Main Authors: Meyer, Abigail R., Taylor, P. Craig, LaSalvia, Vincenzo, Wang, Xue, Nemeth, William, Page, Matthew, Young, David L., Agarwal, Sumit, Stradins, Paul
• Format: Article
• Language: English
• Subjects: defect engineering; energy efficiency; ENGINEERING; hydrogenation; LeTID; light and elevated temperature induced degradation; photovoltaic; PV; silicon solar cells; SOLAR ENERGY
• ISSN: 2666-3864; 2666-3864
• DOI: 10.1016/j.xcrp.2022.101201

Light-induced degradation of Si solar cells when deployed in warmer climates can cause up to a ∼10% relative degradation in efficiency, but the atomic structure of the defect responsible for this degradation remains elusive. Herein, using electron paramagnetic resonance, we show that the defect responsible for light- and elevated-temperature-induced degradation (LeTID) is likely an Si dangling bond within an extended defect such as a vacancy agglomerate, with H atoms in its vicinity and likely O nearby. Our atomistic-level insights suggest that the defect responsible for LeTID can be mitigated by targeted engineering of the intrinsic defect populations by optimizing annealing routines prior to or during device fabrication and by controlling the amount of H injected in the Si bulk during cell processing. Mitigating LeTID through detailed knowledge of its atomic structure can help preserve the long-term efficiency of gigawatts of future worldwide installations of solar based on crystalline Si. [Display omitted] •The defect responsible for LeTID is an Si dangling bond within a vacancy agglomerate•Isotope experiments unambiguously confirm the presence of H in the LeTID defect•The EPR signatures are directly correlated with the extent of degradation observed•These spectroscopic results show atomistic-level details on LeTID Using electron spin resonance, Meyer et al. show the defect responsible for light- and elevated-temperature-induced degradation (LeTID) is likely an Si dangling bond in a vacancy agglomerate, with H atoms in its vicinity and oxygen backbonds. This insight shows that the LeTID defect can be mitigated by targeted defect engineering.