High-Specific Power Flexible Photovoltaics from Large-Area MoS₂ for Space Applications

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Two-dimensional (2D) transition metal dichalcogenides (TMDCs) are promising for photovoltaic (PV) applications due to their unique electronic and optical properties.
• Flexible and lightweight solar cells are highly desirable for space applications, where mass and volume are critical constraints.

Purpose of the Study:

• To model, fabricate, and characterize large-area CVD-grown MoS₂-based flexible PVs for space structures.
• To evaluate the performance, durability, and potential of these 2D PVs under space-relevant conditions, including radiation exposure and mechanical stress.
• To conduct a techno-economic analysis comparing 2D PVs with traditional silicon panels for space deployment.

Main Methods:

• Fabrication of flexible PV devices using large-area CVD-grown MoS₂ monolayers on a polyimide substrate with polyimide encapsulation.
• Characterization of device performance under 1 sun AM0 illumination, including open-circuit voltage (V_OC) and specific power.
• Assessment of device stability through repetitive bending tests and exposure to 1 MeV electron radiation.
• Techno-economic analysis for a 6U CubeSat application.

Main Results:

• Subnanometer-thick MoS₂ monolayer devices achieved a V_OC of 0.180 V and a specific power of 0.001 kW/kg.
• Model projections indicate a potential specific power of 12.97 kW/kg for a 100 nm-thick MoS₂ absorber.
• Devices maintained performance after bending to a 5 mm radius and showed increased performance after radiation exposure, possibly due to defect healing.
• Techno-economic analysis revealed 2D PV arrays offer 2 orders of magnitude higher specific power and lower deployment costs for CubeSats compared to Si panels.

Conclusions:

• Large-area CVD-grown MoS₂-based flexible PVs are suitable for space applications, offering high specific power and radiation tolerance.
• The polyimide encapsulant minimally impacts performance, and thicker MoS₂ layers can significantly boost specific power.
• 2D TMDC-based PVs present a compelling alternative to silicon for space power generation, particularly for small satellite platforms like CubeSats.