Coming, cheaper solar cells with greater efficiency

Scientists have developed a solar-panel material that can pave the way for cheaper solar cells while achieving competitive power-conversion efficiency of 20.2 percent.

Some of the most promising solar cells today use light-harvesting films made from perovskites - a group of materials that share a characteristic molecular structure.

However, perovskite-based solar cells use expensive "hole-transporting" materials whose function is to move the positive charges that are generated when light hits the perovskite film.

Scientists from the Swiss Federal Institute of Technology (EPFL) in Lausanne have 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 percent.

A team of researchers led by Mohammad Nazeeruddin developed a molecularly engineered hole-transporting material called FDT that can bring costs down while keeping efficiency up to competitive levels.

"The best performing perovskite solar cells use hole transporting materials which are difficult to make and purify, and are prohibitively expensive, costing over 300 Euro per gram preventing market penetration," said Nazeeruddin.

"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," he added in a paper published in Nature Energy.

Tests showed that the efficiency of FDT rose to 20.2 percent - higher than the other two, more expensive alternatives.

Because FDT can be easily modified, it acts as a blueprint for an entire generation of new low-cost hole-transporting materials, the authors added.