Perovskite is one of the most promising new materials for solar cell technology. Now, an engineer at the University of Rochester has developed a new method that he more than triples the efficiency of the material by adding a layer of reflective silver underneath it.
Silicon was the go-to material for making solar cells for the better part of a century, thanks to its abundance and efficiency in converting light into electrical current. However, in just the last decade, new candidates have risen rapidly through the ranks. Perovskite is much cheaper and has already caught up with silicon in efficiency.
Now, new research has improved the efficiency of perovskite by 3.5x without tweaking the material itself. Instead, we find that adding a layer of another material underneath alters the interaction of the electrons in the perovskite, reducing the energy-consuming process.
Perovskites and other photovoltaic materials produce electricity when sunlight excites electrons in the material, causing the electrons to fly out of the atoms, ready to be induced and produce electrical current. But sometimes electrons fall into the “holes” left behind, reducing the overall current flow and making the material less efficient. This is what is called electron recombination.
The researchers found that placing the perovskite on a substrate composed of either silver alone or alternating layers of silver and aluminum oxide could significantly reduce electron recombination in the perovskite. Doing so creates a kind of mirror that creates an inverted image of the electron-hole pair, making it less likely that the electron will recombine with the hole, the team says. In tests, the engineer showed that adding these layers increased the efficiency of light conversion by a factor of 3.5.
Chunlei Guo, lead author of the study, said: “As new perovskites emerge, we can use physics-based methods to further improve their performance.”
A study was published in a journal nature photonics.
Source: University of Rochester
