Stored solar power has the potential to be a highly reliable source of renewable energy, especially in areas that are underserved by current power grids, but its high initial cost and the fragility of some systems has undermined its usefulness. One potential solution is the dye-sensitized solar cell, which sandwiches an organic light-absorbing dye between layers of conductive glass, using a method similar to plant photosynthesis. These cells are relatively simple to make, but the electrolytes around the dye break down or leak out within 18 months. That's the problem that a team from Northwestern University hopes it has fixed with a new system based on a version of the dye-sensitized cell called the Grätzel cell.

In a paper recently published in Nature, the team describes how it replaced the electrolytes with a combination of cesium, tin and iodine. This gave the cell an efficiency of around 10.2 percent, a record for non-liquid cells of this type, allowing the compound itself, as well as the dye, to absorb light. The fact that the compound is solid and inorganic also makes it last longer and removes the risk of leakage. This efficiency level is lower than in traditional photovoltaic cells, which can reach over 20 percent. However, as with the somewhat similar "artificial leaf," this could be offset by low cost and ease of manufacturing.