2025-01-10 ミシガン大学
＜関連情報＞
- https://news.umich.edu/light-flexible-and-radiation-resistant-organic-solar-cells-for-space/
- https://www.sciencedirect.com/science/article/abs/pii/S2542435124005142
有機薄膜太陽電池の耐放射線性 Radiation hardness of organic photovoltaics
Yongxi Li, Karthik Kamaraj, Yogita Silori, Haonan Zhao, Claire Arneson, Bin Liu, Jennifer Ogilvie, Stephen R. Forrest
Joule Available online: 9 January 2025
DOI:https://doi.org/10.1016/j.joule.2024.12.001
Graphical abstract
Highlights
- Small-molecule OPVs exhibit strong resilience to proton irradiation
- Polymer-based OPVs experience a decline to 50% of their original efficiency
- The efficiency loss is attributed to polymer cross-linking
- A significant fraction of defects can be rendered inactive by thermal annealing
Context & scale
Lightweight, mechanically and radiation-resilient solar power sources are essential for space-borne platforms such as satellites, propulsion and powering of autonomous vehicles, robots, and space suits. Organic photovoltaic (OPV) cells are a promising solution for this sector due to their ultralight weight, high power conversion efficiency (PCE), flexibility that allows for compact stowage, and exceptional stability when used for terrestrial applications. The continuous advances in organic materials have enabled PCE >20%, making OPVs competitive with other thin-film photovoltaic technologies. The only pervasive myth associated with OPVs is that the materials are intrinsically vulnerable to degradation when exposed to high-energy incident radiation. In this work, we find that small-molecule OPVs grown by vacuum thermal evaporation are resistant to degradation by proton irradiation, in contrast to polymer-based OPVs that suffer a 50% efficiency loss under similar conditions. The loss of efficiency is attributed to cleavage of pendant alkyl groups on the polymers, resulting in cross-linking and the subsequent formation of deep electronic traps. Thermal annealing at low temperatures significantly restores the polymer-based OPV PCE. This example provides a proof-of-concept that OPVs could have exceptional operational lifetimes in space or in other high-energy radiation environments.
Summary
We investigate the resilience of organic photovoltaic (OPV) cells to proton irradiation at doses equivalent to that experienced by spacecraft in low earth orbit. The OPVs, with their inherent flexibility, light weight, low temperature processing, and potential to achieve high specific power of 40 W/g, are promising candidates for energy production in space. However, their ability to withstand irradiation by high-energy incident radiation and subatomic particles characteristic of harsh space environments is yet unproven. We find that small-molecule OPVs grown by vacuum thermal evaporation are resistant to degradation by 30 keV proton irradiation, in contrast to polymer-based OPVs that suffer a 50% efficiency loss under similar conditions. Thermal annealing at low temperatures significantly restores the polymer-based OPV power conversion efficiency. The loss of efficiency is attributed to cleavage of pendant alkyl groups on the polymers, resulting in cross-linking and the subsequent formation of deep electronic traps.
