Cadmium Telluride Photovoltaics for Space Applications

Justification for Exploring Cadmium Telluride Photovoltaics

• The cost of sending payloads into space has decreased significantly due to companies like SpaceX, Boeing, and Blue Origin.
• If this trend continues, using photovoltaic devices with around 20% efficiency in satellite power systems could become viable.

Research Focus: Radiation Hardness

• The research focuses on the radiation hardness of cadmium telluride-based photovoltaic devices.
• Proton and electron radiation are the main factors causing performance degradation and device failure in near-Earth space.

Experimental Setup

• First Solar provided graded cadmium selenide telluride photovoltaic devices doped with either copper or arsenic.
• These devices were sent to Auburn University for irradiation using a two MeV electron accelerator.
• Radiation levels ranged from 150 keV to 1,500 keV for protons.
• The proton influence was 10^9 times 10 to the protons per centimeter squared.
• After irradiation, the devices were characterized, and displacement damage dose modeling was performed.
• The results were compared with commercially available three-five multi-junction technologies.

SHREM and Irradiation Conditions

• SHREM (likely referring to a simulation tool) was used to determine irradiation conditions consistent with displacement damage dose modeling.
• A key assumption of this modeling is that protons pass through the device with relatively unchanged energy, creating uniform damage.
• Proton energies above 500 keV were necessary to ensure they passed through the entire device.
• Most irradiations used protons with energies of 650 keV or higher.
• Some hydrogen doping was done with a 150 keV condition, but it wasn't discussed in detail.

Performance Results

• Box plots show the power conversion efficiency (PCE) remaining factor of the devices after irradiation.