High-efficiency ⁹⁰Sr radio-photovoltaic cells based on waveguide light concentration structure.

Area of Science:

• Materials Science
• Nuclear Engineering
• Energy Conversion

Background:

• Radio-photovoltaic cells (RPVCs) offer high reliability for harsh environments but suffer from limited energy conversion efficiency (ECE) due to their two-stage process.
• Existing RPVC designs struggle to overcome inherent efficiency limitations.

Purpose of the Study:

• To develop a novel RPVC design that enhances energy conversion efficiency and long-term stability.
• To investigate the performance of a waveguide light concentration (WLC) scheme in RPVCs.

Main Methods:

• Designed and fabricated RPVCs using multilayer-stacked GAGG:Ce scintillation waveguides with ⁹⁰Sr radioisotope sources.
• Employed a waveguide light concentration (WLC) scheme to improve light collection.
• Conducted electron beam irradiation tests to evaluate radioluminescence (RL) and long-term stability.

Main Results:

• Achieved a record ECE of 2.96% for a single RPVC prototype powered by ⁹⁰Sr, delivering 48.9 μW maximum output power.
• Demonstrated a multi-module prototype with 3.17 mW maximum output power, 2.23 mA short circuit current, and 2.14 V open circuit voltage.
• Exhibited exceptional radiation hardness with only 13.8% RL degradation after 50-year equivalent electron beam irradiation.

Conclusions:

• The WLC-based RPVC design significantly improves both power output and long-term stability.
• This advancement represents a substantial step towards practical nuclear battery applications.
• The developed RPVCs show great promise for reliable power in demanding environments.