The unusual development comes from a collaborative effort between researchers based at University of California, Los Angeles (UCLA) and Solargiga Energy in China. The idea of using caffeine was serendipitous, according to lead researcher Professor Jingjing Xue, when the researchers were joking that if they needed coffee to feel better in the mornings then what about perovskites?
Perovskite is a calcium titanium oxide mineral composed of calcium titanate, and found in the Earth’s mantle. The mineral is used with one type of solar cell. A perovskite solar cell includes a perovskite structured compound, generally as a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer. By possessing a high absorption coefficient, this enables ultrathin films of around 500 nanometers to be used as solar cells and these types of cells can absorb the complete visible solar spectrum. This opens up applications like using windows as solar capture and energy generating solar technologies.
For the research, the scientists noted that caffeine in coffee is an alkaloid compound, which contains molecular structures that can interact with the precursors of perovskite materials and this might improve the thermal stability of solar cells and boost the cells’ efficiency.
In trials, the research team added caffeine to the perovskite layer of forty solar cells. They next applied infrared spectroscopy to identify chemical compounds and used this data to determine how well the caffeine bonds with the material (particularly lead ions). Fine tuning this, enabled them to run tests as to the solar cell efficiency. The tests showed that solar cell efficiency had been boosted by between 17 and 20 percent.
Based on the series of experiments, the addition of caffeine appears to aid the perovskite to achieve higher crystallinity, lower defects, and improved stability. It is hoped that the unusual research will assist with developing a more cost-effective form of the renewable energy technology and to introduce an alternative to silicon solar cells, to co-compete within the growing solar energy market.
The research has been published in the science journal Joule, with the peer reviewed paper headed “Caffeine Improves the Performance and Thermal Stability of Perovskite Solar Cells.”
