Cheaper, longer-lasting perovskite solar cells could be on the way

Perovskite solar cells are one of the most exciting green energy technologies to emerge in recent years, combining low cost with high energy conversion rates. Now, researchers at the Swiss Federal Institute of Technology in Lausanne (EPFL) have found a way to cut their cost even further by developing a charge-carrying material that is much cheaper, highly efficient, and could even help address the technology's current major weakness by significantly lengthening the lifespan of the panels.

Record efficiencies for solar cells tend to grab all the headlines, but it is other less flashy metrics – such as price per watt – that provide a much fairer assessment of whether a new technology can produce clean energy on the global scale. Perovskite solar cells excel in this area by combining low cost with efficiencies that have already surpassed the 20 percent mark, rivaling standard silicon-based panels while also being, according to a recent study, easier on the environment than any of the best-known alternatives in the solar arena.

But before perovskite cells can make it to mass production, one big issue still remains to be addressed: the outer shell of the panel, the function of which is to conduct electric charge, is made from organic compounds that will quickly wither away in real-life conditions, cutting the life of the cell to a few short months.

Researchers led by Mohammad Nazeeruddin at EPFL have now developed a new inorganic conductive material for perovskite cells that is cheaper, still allows for high energy conversion rates and, more importantly, offers plenty of wiggle room for experimentation, paving the way for longer-lasting, cost-effective perovskite panels.

The new material, dissymmetric fluorene–dithiophene (FDT), is said to cost less than one fifth to synthesize than previous compounds (US$60 versus $500 per gram) while still retaining a very competitive energy conversion rate of 20.2 percent.

"The previous material (Spiro) was rather difficult to synthesise and purify in large scale, preventing perovskite solar cells market penetration," Nazeeruddin told Gizmag. "It is also well known in the literature that the stability of Spiro is limited. We are doing stability measurements of the new material: if the stability is established, the economic benefits would be enormous."

While no determination has yet been made on the stability of the compound used in the study, two considerations leave room for optimism. First, the inorganic nature of the compound is expected to make it more resistant to weather and biodegradation. And secondly, the FTD core material can be reportedly modified with ease, creating not one, but a family of compounds.

The hope is that this amount of wiggle room will be enough for researchers to engineer a material that is both cheap, long-lasting, and still allowing for efficiencies that are competitive with respect to the final price of the panel.

A paper describing the advance appears in the journal Nature Energy.

Source: EPFL