Material achieves 20.2% efficiency & lowers PV cost

Publishing in Nature Energy, EPFL scientists have now engineered a considerably cheaper hole-transporting material that costs only a fifth of existing ones while keeping the efficiency of the solar cell above 20%.

As the quality of perovskite films increases, researchers are seeking other ways of improving the overall performance of solar cells. Inadvertently, this search targets the other key element of a solar panel, the hole-transporting layer and specifically, the materials that make them up. There are currently only two hole-transporting materials available for perovskite-based solar cells. Both types are quite costly to synthesise, adding to the overall expense of the solar cell.

To address this problem, a team of researchers led by Mohammad Nazeeruddin at EPFL developed a molecularly engineered hole-transporting material, called FDT, that can bring costs down while keeping efficiency up to competitive levels. Tests showed that the efficiency of FDT rose to 20.2% - higher than the other two, more expensive alternatives. And because FDT can be easily modified, it acts as a blueprint for an entire generation of new low-cost hole-transporting materials.

Nazeeruddin commented: "The best performing perovskite solar cells use hole transporting materials, which are difficult to make and purify and are prohibitively expensive, costing over €300 per gram, preventing market penetration. By comparison, FDT is easy to synthesise and purify and its cost is estimated to be a fifth of that for existing materials – while matching and even surpassing their performance.”