Perovskite is one of the most promising new materials for solar cell technology . Now, engineers at the University of Rochester have developed a new way to more than triple the efficiency of the material by adding a layer of reflective silver underneath.
Until now, silicon has been the reference material for making solar panel cells, mainly due to its abundance and efficiency in converting light into electrical current. But in recent times, perovskite has been questioning the dominance of silicon, since it is much cheaper and has already caught up with silicon in efficiency.
Increasing the efficiency of the perovskite
This parity in efficiency between perovskite and silicon is set to change thanks to research work by engineers at the University of Rochester. Their new study has increased the efficiency of the perovskite by three and a half times , without even changing the material itself. Instead, the research team found that adding a layer of a different material underneath changed the interactions of the electrons in the perovskite, reducing an energy-depleting process.
Perovskites and other photovoltaic materials generate electricity by allowing sunlight to excite the material’s electrons, causing them to jump out of their atoms, ready to be guided and generate an electrical current. But sometimes, the electrons fall back into the “holes” they left behind, reducing the overall current, and as such, the efficiency of the material. This is what is known as electron shuffling .
Solar panels with silver
Researchers at the University of Rochester found that they could drastically reduce electron recombination in the perovskite by placing it on a substrate composed of silver alone or alternating layers of silver and aluminum oxide .
The team says that doing so creates a kind of mirror that produces inverted images of the electron-hole pairs, reducing the likelihood that the electrons will recombine with the holes. In tests, engineers showed that adding these layers increased light conversion efficiency by 3.5 times .
“A piece of metal can do as much work as complex chemical engineering in a laboratory,” said Chunlei Guo, lead author of the study. “ As new perovskites emerge, we can use our physics-based method to further improve their performance. “
“No one else has arrived at this observation in perovskites. Suddenly, we can put a metal platform under a perovskite, completely changing the interaction of the electrons inside the perovskite. Therefore, we use a physical method to design that interaction,” concludes Guo.