What you’ll learn:
- How beta particles can be used to generate power.
- The challenges of building a cell based on beta particles.
- How some of these limitations were overcome.
- The remaining harsh realities of cells based on beta particles.
Researchers at the Daegu Gyeongbuk Institute of Science & Technology (DGIST), Republic of Korea, have achieved what they claim is a significant breakthrough by creating the world’s first next-generation “betavoltaic” cell. This advanced power source was made by directly connecting a radioactive isotope’s electrode emitting beta particles to a perovskite absorber layer, a cutting-edge material known for its efficiency. In theory, this harvesting could lead to long-life, pocket-sized power sources.
Perovskite, a calcium-titanium-oxide mineral, has been known since the early 1800s. Its name is also applied to the class of compounds that have the same type of crystal structure as CaTiO3, known as the perovskite structure, and has a general chemical formula ABX3 where A and B are cations and X is an anion, often oxides or halides.
Perovskites offer advantages such as high power-conversion efficiency, tunable bandgaps, and potentially lower production costs compared to traditional silicon solar cells. However, they also face challenges related to stability and long-term performance. As with graphene and other intriguing materials, there’s lots of investigative research being done on diverse and non-obvious applications for perovskites.
What’s a Betavoltaic Cell?
Betavoltaic cells generate electricity by capturing beta (β) particles emitted during the natural radioactive decay. Betavoltaic devices have a radioactive isotope as the energy source, a β-radiation absorbing material for energy conversion, and a counter electrode. (Note that this betavoltaic principle is not the same as using the long-lasting heat of radioactive decay and thermocouples in thermoelectric generators, or TEGs.)
The β-radiation-absorbing material plays a critical role in converting radiation energy into electrical energy, directly influencing the cell’s efficiency and stability. The energy conversion efficiency (ECE) of these devices is currently below 4%, and they have a maximum output power under 500 mW.
In theory, they can operate for decades without maintenance. Beta particles also offer some important biological-safety advantages, as they can’t penetrate human skin. Nevertheless, practical progress has been limited due to the challenges of handling radioactive materials and ensuring material stability.
A New Strategy to Boost Energy Conversion Efficiency
To enhance β-radiation absorption, new material strategies are needed. To boost performance, the DGIST team embedded carbon-14-based quantum dots into the electrode and improved the structure of the perovskite layer. These innovations led to a highly stable power output and relatively impressive ECE (Fig. 1); the key word here is “relatively.”